Keywords:

Survival

Feed conversion

Mineral supplementation

Low salinity

Post larvae

Eect of dietary ion supplementation on the survival and growth of Penaeus vannamei during

the pre-nursery stage in well water

Efecto de la suplementación dietaria con iones sobre el crecimiento y supervivencia de Penaeus

vannamei en precría con agua de pozo

Efeito da suplementação dietética com íons sobre o crescimento e a sobrevivência de Penaeus

vannamei em pré-cria com água de poço´

Juan P. Ordoñez-Iglesias

Agustin N. Zambrano-Ostaiza

Yuniel Méndez-Martínez

Rev. Fac. Agron. (LUZ). 2025, 42(3): e254242

ISSN 2477-9407

DOI: https://doi.org/10.47280/RevFacAgron(LUZ).v42.n3.XIII

Animal production

Associate editor: Dra. Rosa Razz

University of Zulia, Faculty of Agronomy

Bolivarian Republic of Venezuela

Universidad Técnica Estatal de Quevedo (UTEQ), Facultad

de Ciencias Pecuarias y Biológicas, Experimental Aquaculture

Laboratory, Av. Quito Km. 11½ vía Santo Domingo de los

Tsáchilas, Quevedo, 120301, Ecuador

Received: 13-05-2025

Accepted: 15-08-2025

Published: 04-09-2025

Abstract

Aquaculture has become an essential activity to ensure global

food security, with white shrimp (Penaeus vannamei) standing out

as one of the most important species due to its high demand and

adaptability to diverse environments. This study aimed to evaluate

the eect of dietary ion supplementation on the survival, growth

and feed eciency of P. vannamei during the pre-nursery stage

using well water. The experiment included a control treatment (T0)

with seawater (34 ppt) and no added ions, and three treatments

using well water and ion-supplemented diets: T1 (0.1 mg Ca²⁺, 1.2

mg Mg²⁺, 0.4 mg K⁺), T2 (0.2 mg Ca²⁺, 2.2 mg Mg²⁺, 0.8 mg K⁺),

and T3 (0.4 mg Ca²⁺, 4.2 mg Mg²⁺, 1.4 mg K⁺). Each treatment

consisted of three replicates, with 50 post-larvae per tank, over a

28-day period. Statistically signicant dierences (p<0.05) were

observed in survival, growth and feed conversion ratio (FCR). The

highest growth (1.03 %) was recorded in T0, followed by T2 (0.91

%) and T3 (0.83 %), while T1 showed the lowest growth (0.68 %)

and the best FCR (1.027). Treatment T3 showed a favorable balance

between growth and survival (94.5 %) with a competitive FCR

(1.091). It is concluded that dietary ion supplementation improves

the zootechnical performance of P. vannamei cultured in well water,

and that appropriate adjustment of Ca²⁺, Mg²⁺ and K⁺ concentrations

in feed can optimize both survival and feed eciency under low-

salinity conditions.

This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.

Rev. Fac. Agron. (LUZ). 2025, 42(3): e254242 July-September. ISSN 2477-9409.

2-7 |

Resumen

La acuicultura se ha convertido en una actividad esencial para

garantizar la seguridad alimentaria global, siendo el camarón blanco

(Penaeus vannamei) una de las especies más importantes por su

alta demanda y capacidad de adaptación a diversos entornos. Este

estudio tuvo como objetivo evaluar el efecto de la suplementación

dietaria con iones sobre la supervivencia, crecimiento y la eciencia

alimenticia de P. vannamei durante la etapa de precría utilizando agua

de pozo. El experimento incluyó un tratamiento control (T0) con agua

de mar (34 ppt) sin adición de iones, y tres tratamientos con agua de

pozo y dietas suplementadas: T1 (0,1 mg Ca²⁺, 1,2 mg Mg²⁺, 0,4 mg

K⁺), T2 (0,2 mg Ca²⁺, 2,2 mg Mg²⁺, 0,8 mg K⁺) y T3 (0,4 mg Ca²⁺, 4,2

mg Mg²⁺, 1,4 mg K⁺). Cada tratamiento tuvo tres repeticiones con 50

postlarvas por tanque, durante un periodo de 28 días. Se detectaron

diferencias signicativas (p<0,05) en supervivencia, crecimiento y

factor de conversión alimenticia (FCA). El mayor crecimiento (1,03

%) se registró en T0, seguido de T2 (0,91 %) y T3 (0,83 %), mientras

que T1 presentó el menor crecimiento (0,68 %) y mejor FCA (1,027).

Sin embargo, el tratamiento T3 alcanzó un equilibrio favorable

entre crecimiento y supervivencia (94,5 %), con una eciencia

alimenticia competitiva (1,091). Se concluye que la suplementación

iónica en dietas permite mejorar el rendimiento zootécnico de P.

vannamei cultivado en agua de pozo, y que el ajuste adecuado de las

concentraciones de Ca²⁺, Mg²⁺ y K⁺ en el alimento puede optimizar

tanto la supervivencia como la conversión alimenticia, especialmente

en condiciones de baja salinidad.

Palabras clave: supervivencia, conversión alimenticia,

suplementación mineral, postlarvas, baja salinidad.

Resumo

A aquicultura tornou-se uma atividade essencial para garantir

a segurança alimentar global, destacando-se o camarão-branco

(Penaeus vannamei) como uma das espécies mais importantes devido

à sua alta demanda e adaptabilidade a diversos ambientes. Este estudo

teve como objetivo avaliar o efeito da suplementação dietética com

íons sobre na sobrevivência, crescimento e na eciência alimentar

de P. vannamei durante a fase de pré-cria utilizando água de poço. O

experimento incluiu um tratamento controle (T0) com água do mar

(34 ppt) sem adição de íons, e três tratamentos com água de poço e

dietas suplementadas com íons: T1 (0,1 mg Ca²⁺, 1,2 mg Mg²⁺, 0,4

mg K⁺), T2 (0,2 mg Ca²⁺, 2,2 mg Mg²⁺, 0,8 mg K⁺) e T3 (0,4 mg Ca²⁺,

4,2 mg Mg²⁺, 1,4 mg K⁺). Cada tratamento teve três repetições com

50 pós-larvas por tanque, durante um período de 28 dias. Diferenças

signicativas (p<0.05) foram observadas na sobrevivência,

crescimento e na taxa de conversão alimentar (TCA). O maior

crescimento (1,03 %) foi registrado no T0, seguido de T2 (0,91 %) e

T3 (0,83 %), enquanto o T1 apresentou o menor crescimento (0,68 %),

e a melhor TCA (1,027). O tratamento T3 demonstrou um equilíbrio

favorável entre crescimento e sobrevivência (94,5 %), com uma TCA

competitiva (1,091). Conclui-se que a suplementação dietética com

íons melhora o desempenho zootécnico de P. vannamei cultivado em

água de poço, e que o ajuste adequado das concentrações de Ca²⁺,

Mg²⁺ e K⁺ na ração pode otimizar tanto a sobrevivência quanto a

eciência alimentar em condições de baixa salinidade.

Palavras-chave: sobrevivência, conversão alimentar, suplementação

mineral, pós-larvas, baixa salinidade.

Introduction

Shrimp aquaculture has emerged as one of the fastest-growing

sectors in global aquaculture, with Penaeus vannamei (Pacic white

shrimp) dominating the market due to its rapid growth, high survival

rates, and high salinity tolerance (Morales-Cristobal et al., 2022;

Campa-Córdova et al., 2024). This euryhaline species can thrive

in environments ranging from marine waters to near-freshwater

conditions (0.5–45 ppt), making it suitable for inland farming systems

where access to seawater is limited (Saraswathy et al., 2020). The

expansion of inland aquaculture using well water oers a promising

alternative to traditional coastal systems, helping to reduce the

incidence of diseases such as white spot syndrome virus (WSSV),

Taura syndrome virus (TSV), and infectious hypodermal and

hematopoietic necrosis virus (IHHNV) (Roy et al., 2010; Ordoñez-

Iglesias et al., 2024).

Despite its adaptability, culturing P. vannamei in low-salinity or

well water presents several physiological challenges, particularly

concerning osmoregulation. Shrimp expend considerable energy to

maintain osmotic homeostasis when exposed to ionic compositions

that dier from their natural habitat. This often results in impaired

growth, reduced feed intake, and increased mortality (Huong et

al., 2010; Saraswathy et al., 2020). Ionic imbalances, especially

deciencies in calcium (Ca²⁺), magnesium (Mg²⁺), and potassium

(K⁺), have been identied as critical limiting factors in low-salinity

shrimp culture systems (Gil-Núñez et al., 2020; Valenzuela-Madrigal

et al., 2017).

The composition of inland waters, particularly well water,

often lacks the appropriate ionic ratios essential for optimal shrimp

performance (Gil-Núñez et al., 2020; Song et al., 2025). Studies

show that suboptimal concentrations of macrominerals not only

aect osmoregulation but also compromise immune responses,

nutrient absorption, and muscle function (Valenzuela-Madrigal

et al., 2017; Saraswathy et al., 2020). To mitigate these eects,

dietary supplementation with essential ions has been proposed as a

viable strategy to support physiological homeostasis in low-salinity

environments (Li and Liu, 2017).

Recent research has shown promising results from supplementing

shrimp diets with Ca²⁺, Mg²⁺, and K⁺ to enhance performance in ion-

decient systems. For instance, Ordoñez-Iglesias et al. (2024) reported

signicant improvements in survival, gut integrity, lipid reserves,

and molting frequency in P. vannamei postlarvae reared in well water

supplemented with these ions. The most favorable outcomes were

observed in the treatment containing 0.4 mg.L

-1

of Ca²⁺, 4.2 mg.L

-1

of Mg²⁺, and 1.4 mg.L

-1

of K⁺, which also showed reduced stress

markers such as necrosis and expanded chromatophores.

Understanding the osmoregulatory physiology of P. vannamei is

essential for developing eective ion supplementation strategies. This

species exhibits strong hyperosmotic regulatory capacity, maintaining

serum osmolality within a narrow range even when ambient salinity

drops drastically (Saraswathy et al., 2020). The Na⁺/K⁺-ATPase

enzyme plays an essential role in this process by actively transporting

ions across gill membranes, sustaining the ionic gradients required for

homeostasis (Lucu and Towle, 2003). In parallel, dietary formulation

also inuences shrimp performance under ionic stress.

Gil-Núñez et al. (2020) examined the eect of varying protein

sources and levels on P. vannamei reared at 3 ppt of salinity, nding

that sh meal (FM) based diets outperformed soy meal (SM) based

alternatives in terms of growth rate, protein eciency, and survival.

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3-7 |

These diets also contained higher levels of ash, calcium, iodine,

phosphorus, and sodium, further supporting the idea that mineral-rich

feeds can enhance shrimp tolerance to ionic uctuations. Moreover,

experimental data from Saraswathy et al. (2020) and Méndez-Martínez

et al. (2021), demonstrated that P. vannamei maintained high survival

and stable serum osmolality under both gradual and abrupt salinity

reductions. Notably, survival was 100 % during gradual reductions

down to freshwater and 95 % under abrupt reductions to 5 ppt.

Integrating mineral supplementation into shrimp diets is not

only a physiological necessity but also an economically strategic

approach. In systems where direct manipulation of water chemistry

is not feasible, feed-based supplementation oers a practical and

scalable solution (Rubio et al., 2012). Furthermore, designing

species- and system-specic diets can increase feed eciency,

reduce environmental discharge, and enhance overall sustainability

(Méndez-Martínez et al., 2021; Song et al., 2025).

The growing interest in optimizing inland aquaculture practices

has spurred investigations into the ideal ionic compositions and

supplementation methods for low-salinity systems. Several studies

recommend maintaining ionic ratios close to seawater to reduce energy

expenditure on osmoregulation (Gil-Núñez et al., 2020; Saraswathy

et al., 2020). However, the availability of mineral resources, cost,

and digestibility must also be considered when implementing such

strategies.

Given this context, the present study aims to evaluate the eect

of dietary ion supplementation, specically Ca²⁺, Mg²⁺, and K⁺, on

the growth performance and survival of Penaeus vannamei during

the pre-rearing stage in well water. This developmental phase is

particularly sensitive, as postlarvae transition from hatchery to

grow-out environments, where nutritional and environmental factors

critically inuence survival and long-term performance (Lucu and

Towle, 2003). The ndings will contribute to the expanding body

of knowledge on functional feed development and water quality

management for sustainable shrimp aquaculture.

Materials and methods

Experimental Location and Design

The study was conducted in October 2023 at the Aquaculture

Laboratory of the Universidad Técnica Estatal de Quevedo (UTEQ),

located in Quevedo, Los Ríos, Ecuador, at an altitude of 73 meters

above sea level. The geographical coordinates are 01°06’13” S

latitude and 79°29’22” W longitude.

A completely randomized design (CRD) was used, consisting

of four treatments: one control (T0) and three levels of ionic

supplementation (T1, T2, and T3), each with three replicates.

Experimental units consisted of 40-L plastic tanks, each stocked with

50 postlarvae, for a total of 600 shrimp. The experimental period

lasted 28 days. Table 1 shows the concentrations of supplemented

ions for each treatment. The control treatment (T0) was maintained

with seawater at 34 ppt, while the other treatments used freshwater

from a well.

Table 1. Ion concentrations used in each treatment.

Treatment Ca²⁺ (mg.L

-1

) Mg²⁺ (mg.L

-1

) K⁺ (mg.L

-1

)

T0 (control) 0.0 0.0 0.0

T1 0.1 1.2 0.4

T2 0.2 2.2 0.8

T3 0.4 4.2 1.4

Experimental Design

Postlarvae of Penaeus vannamei, 12 days old, were collecteed

from the Biogemar S.A. hatchery, located in the province of Santa

Elena, Ecuador, and transported by land in plastic bags to the

experimental site. Upon arrival, shrimp were gradually acclimated by

mixing the transport water with the tank water, reducing salinity at a

rate of 1 ppt per hour until reaching 0 ppt, to avoid mortality due to

osmotic shock.

As shown in table 2, the well water used in the treatments was

previously analyzed for quality, measuring the concentrations of

cations (Na⁺, K⁺, Mg²⁺, Ca²⁺) and anions (carbonates, bicarbonates,

sulfates, and chlorides) (Federation and Aph Association, 2005).

Water quality parameters were monitored daily using a CCOWAY

multiparameter sound, and an ATC refractometer.

Table 2. Physicochemical analysis of well water.

Parameter

(mg.L

-1

)

Level

Ca²⁺ 5.24

Mg²⁺ 1.94

Na⁺ 8.09

K⁺ 2.63

CO₃ 0.02

HCO₃ 17.08

Cl 17.50

SO₄ 2.47

Cations and anions studied in the well water used for the experiment.

Weekly measurements of Ca²⁺, Mg²⁺, and K⁺ concentrations in

each tank, were performed using colorimetric titration with a Monitor-

brand water testing kit, and values were expressed in ppm (mg.L

-1

Ionic Supplementation in the Feed

Three experimental diets were formulated by adding varying

concentrations of Ca²⁺, Mg²⁺, and K⁺ by spraying them directly onto

the commercial feed Nicovita (0.8 mm pellet size)(table 3), based

on the calculated requirements to simulate seawater-like conditions,

followed by drying the feed in the shade at 26 °C for 4 hours. The

ionic solutions were prepared by mixing liquid forms of the ions, and

no binders were required, as the mixture did not leach into the water

during feeding. Feed was oered four times per day at 8:00 a.m.,

11:00 a.m., 2:00 p.m., and 5:00 p.m.

Table 3. Nutritional composition of the Nicovita 0.8 mm

commercial feed used in the experiment.

Component Value

Crude protein

Crude fat

Moisture

Ash

Crude ber

Calcium Carbonate

Sodium Chloride

Potassium Phosphate

Sodium Phosphate

Vitamin and Mineral Premix (Copper, Zinc, Magnesium, Iodine,

Selenium, Iron, Vitamin A, Vitamin D₃, Vitamin E)

35 %

5 %

12 %

8 %

13%

1.50%

1.40%

0.10%

0.30%

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4-7 |

Table 4. Physicochemical characteristics of water across experimental treatments (average of daily measurements over a 28-day period).

Variable T0 T1 T2 T3 P

Temperature (

C) 25.05±0.09a 25.53±0.10a 25.46±0.4a 25.43±0.49a 0.175

Dissolved Oxygen (mg.L

-1

) 4.67±0.85a 3.57±2.66a 4.39±1.65a 4.56±2.60a 0.629

pH 7.97±0.21a 8.51±0.40c 8.43±0.70bc 8.34±0.19b 0.045

Salinity (%) 35.50±0.0a 2.50±0.02c 2.5±0.0b 2.5±0.0b 0.030

Mean values ± Standard Deviation. Dierent letters are signicantly dierent (p< 0.05).

The requirement for these cations and anions decreases if salinity

decreases (for example, due to dilution with rainwater or freshwater

input), and the concentration of ions (cations and anions) decreases.

This is because the water becomes diluted, and although the types of

ions present may remain the same, their quantity per liter of water is

lower.

Survival and growth

During the 28-day trial, shrimp growth was recorded every

7 days, measuring weight with an analytical balance and length

with a millimeter adhesive ruler. Data collection and management

were facilitated using the Larvia mobile application. Additional

performance indicators, including survival rate and feed conversion

ratio (FCR), were also evaluated to assess the eects of Ca²⁺, Mg²⁺

and K⁺ levels on shrimp development and productivity.

The following formulas were used (Jaer et al., 2019):

Specitical Growth Rate (SGR, %/day) = [(Final weight (g) −

Initial weight (g)) / Days] × 100

Survival Rate (%) = (Final number of shrimp / Initial number of

shrimp) × 100

Feed Conversion Ratio (FCR) = Feed supplied (g) / Biomass

gained (g)

Statistical Analysis

To determine signicant dierences between treatments regarding

growth parameters and water quality an analysis of variance (ANOVA)

was applied to the collected data. Prior to ANOVA, data were tested

for normality (Shapiro Wilks) and homogeneity of variances (Levene)

(Lucu and Towle, 2003). When signicant dierences were found (p<

.05), Tukey‘s post hoc test was used to identify specic dierences

between means. Software STATISTICA 10.0 (StatSoft, Inc., USA)

was used. A signicance level of 5 % is reported. The linear model

used was as follows:

Yᵢⱼ = μ + τᵢ + εᵢⱼ

Where:

Yᵢⱼ: Observation corresponding to treatment i and repetition j

μ: Overall average of all observations

τᵢ: Eect of treatment i (dierence between the mean of treatment

i and the overall mean)

εᵢⱼ: Random error associated with observation ij, it is assumed that

εᵢⱼ ~ N(0, σ²).

Results and discussion

Physicochemical parameters in water

Physicochemical water parameters are critical determinants

during the nursery phase of whiteleg shrimp (Penaeus vannamei),

particularly when well water is used as the culture medium. In

this study, temperature remained stable across treatments with no

signicant dierences (p>0.05), and values ranged from 25.04 to

25.53 °C (table 4). These ndings align with those reported by Castillo

and Velásquez (2021), who stated that the optimal temperature range

for this species lies between 25 and 32 °C. Thermal stability favours

metabolism and growth, and prevents hepatopancreatic dysfunction,

as observed at temperatures below 20 °C (Wang et al., 2019).

Regarding salinity, highly signicant dierences (F=3.20;

p<0.05) were observed between the control treatment (T0) and those

supplemented with ions. T0 maintained a constant salinity of 35.5

± 0.00 ppt, while treatments T1, T2, and T3 ranged from 2.50 ppt.

Although these values are markedly lower than typical seawater

salinity, they showed a slight increase proportional to the dose of

supplemented ions. This pattern suggests a possible ionic release

from the feed into the water column, as proposed by Ordoñez-

Iglesias et al. (2024), without producing a measurable impact on total

salinity. Previous studies have shown that P. vannamei can tolerate a

broad salinity range (0.5 to 40 ppt). However, under reduced salinity

conditions, adequate ionic support is necessary to avoid physiological

impairment (Saraswathy et al., 2020; Amir et al., 2021).

In terms of pH, signicant dierences (F=2.25; p<0.05) were

detected, ranging from 7.97 in T0 to 8.5 in T1. All treatments remained

within P. vannamei optimal range of 6.5 to 9.0 (Furtado et al., 2011).

The higher pH values in the ion-supplemented treatments may be

attributed to the slightly alkaline nature of the mineral compounds

used, such as calcium carbonate and sodium bicarbonate, as reported

by Furtado et al. (2011). This alkalinity can enhance enzymatic

activity and reduce ammonia toxicity.

About dissolved oxygen, no signicant dierences (F=0.83;

p>0.05) were detected between treatments, ranging from 3.57 to 4.67

mg.L

-1

. Although these values are slightly below the optimal range

of 4.0–6.6 mg.L

-1

proposed by Galkanda-Arachchige et al. (2020),

we suggest they were sucient to maintain essential physiological

functions. Nevertheless, levels near the lower threshold may represent

a risk under conditions of higher stocking density or organic load. In

this context, adequate aeration and continuous monitoring are essential

to ensure system stability. Overall, the physicochemical parameters

observed may support the feasibility of using diets supplemented with

Ca²⁺, Mg²⁺ and K⁺ as a strategy to improve environmental quality in

low-salinity systems, contributing to ionic homeostasis and improved

shrimp performance (Furtado et al., 2011).

Highly signicant dierences (F=3.00, F=2.95, F=3.09, p<0.05)

were also observed in the concentrations of these essential ions (Ca²⁺,

Mg²⁺ and K⁺) between the control (T0) and treatments T1, T2, and T3,

suggesting a direct response to the progressive inclusion of minerals

in the feed (gure 1), respectively. These results are consistent with

Galkanda-Arachchige et al. (2020), who demonstrated that mineral

supplementation increases the concentration of key ions in the culture

water, thus enhancing osmotic homeostasis.

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5-7 |

Figure 1. Ionic concentration in water across experimental

treatments (average of daily measurements over a 28-

day period).

In the case of calcium (Ca²⁺), a proportional increase was observed

with each supplementation level. This is particularly relevant given

its structural role in exoskeleton formation and its involvement in

physiological processes such as muscle contraction and hemolymph

coagulation (Valenzuela-Madrigal et al., 2017). Similar results

were reported by Amir et al. (2021), who observed signicant

improvements in survival and weight gain in shrimp cultured in

brackish water following dietary Ca²⁺ supplementation. Likewise,

the work of Ordoñez-Iglesias et al. (2024) under similar conditions

demonstrated that supplementation with 0.4 mg.L

-1

of Ca²⁺ reduced

necrosis incidence and supported tissue integrity.

Magnesium (Mg²⁺) levels also increased with supplementation.

This ion plays a critical role in enzymatic processes, neuromuscular

regulation, and osmoregulation (Abdelrahman et al., 2023). Studies

by Galkanda-Arachchige et al. (2020) suggest that increasing

Mg²⁺ levels in water or feed improves weight gain and survival

rates, especially in low-salinity environments. The present ndings

reinforce this view, as treatments with higher Mg²⁺ levels (T2 and

T3) demonstrated better zootechnical performance compared to T1

and the control.

As for potassium (K⁺), a clear upward trend was observed in

the supplemented treatments, highlighting its importance in Na⁺/

K⁺-ATPase activity, which is key to transmembrane ionic regulation

(Lucu and Towle, 2003). Previous studies have linked potassium

deciencies to osmotic dysfunction, reduced appetite, and oxidative

stress (Rubio et al., 2012; Saraswathy et al., 2020). This experiment

validates those ndings, as treatments with higher dietary K⁺ levels

achieved improved survival rates and growth. Experimental evidence

from Amir et al. (2021) further supports these outcomes, showing that

increased dietary K⁺ improve feed conversion ratio (FCR) and body

mass in shrimp reared in brackish systems.

Taken together, these results demonstrate that the strategic

incorporation of Ca²⁺, Mg²⁺ and K⁺ into shrimp diets cultured in

well water not only improves the ionic quality of the environment

but also actively contributes to the animals‘ physiological and health

performance. This strategy is particularly relevant in contexts where

direct water manipulation is limited or costly, positioning functional

diets as an eective and scalable tool (Gil-Núñez et al., 2020).

The cations and ions present in the feed can improve the

properties of well water. They can improve conductivity by increasing

ionic concentrations. Excessive calcium and magnesium ions can

negatively increase water hardness. They can also negatively aect

the increase in ammonium and nitrite levels in the water body if

bioltration is lacking, which contrasts with the increase or decrease

in pH (Saraswathy et al., 2020).

Zootechnical Parameters

The results of this study revealed signicant dierences (p< 0.05)

among treatments in terms of survival, growth, and feed eciency

(table 5). Beginning on day seven, signicant dierences in length

and weight, were observed between treatments, suggesting that ionic

supplementation had a positive eect on somatic growth of Penaeus

vannamei postlarvae. Treatment T1 consistently recorded the highest

weight and length values, while T0 showed the lowest, suggesting

that a diet without ionic supplementation was insucient to meet the

growth requirements. These ndings align with those reported by

Gil-Núñez et al. (2020), who demonstrated that supplementation with

specic mineral salts can signicantly improve growth performance

in low-salinity systems. The consistency in standard deviations across

replicates further supports the reliability of the results obtained.

Table 5. Zootechnical parameters of the beds under the experimental treatments.

Sampling Variable T0 T1 T2 T3 P

Initial

Weight (mg) 6.99±0.10a 6.99±0.11a 6.99±0.09a 6.99±0.12a 0.077

Length (mm) 9.12±0.15a 9.12±0.16a 9.12±0.18a 9.12±0.16a 0.096

7 days

Weight (mg) 85.77±1.036a 99.75±2.63c 97.84±0.86c 92.48±0.46b 0.018

Length (mm) 11.74±0.58a 13.12±0.60c 12.80±0.60b 12.32±0.45b 0.029

14 days

Weight (mg) 190.21±0.98a 202.61±2.29b 199.22±1.66b 190.59±1.26a 0.022

Length (mm) 17.05±0.56a 18.59±0.35b 18.01±0.22b 17.37±0.37a 0.001

21 days

Weight (mg) 411.48±1.04a 478.32±2.87d 466.74±3.76c 454.32±1.91b 0.039

Length (mm) 22.82±0.48a 23.71±1.11b 22.97±1.13a 22.62±0.83a 0.039

28 days

Weight (mg) 721.77±1.22a 795.23±9.47d 775.13±6.78c 758.70±7.34b 0.035

Length (mm) 26.7±0.74a 27.58±2.42b 27.64±1.14b 26.95±1.11a 0.228

Specic Growth Rate 0.68±0.10ª 1.03±0.08c 0.83±0.03b 0.83±0.02b 0.001

Survival Rate (%) 100.00±0.07c 51.33±1.20a 60.67±4.60b 94.67±1.21c 0.001

Feed Conversion Rate 1.186±0.10a 1.027±0.07b 1.074±0.04b 1.091±0.01b 0.468

Mean values ± Standard Deviation. Dierent letters are signicantly dierent (p<0.05)..

This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.

Rev. Fac. Agron. (LUZ). 2025, 42(3): e254242 July-September. ISSN 2477-9409.

6-7 |

From a physiological standpoint, the improvement in growth

observed in the supplemented treatments may be attributed to enhanced

osmoregulatory capacity, facilitated by the adequate availability of

essential ions such as Ca²⁺, Mg²⁺, and K⁺. These cations play a central

role in cellular metabolism, tissue structural stability, and the molting

process in crustaceans (Juniarti et al., 2022). Calcium, in particular, is

fundamental for exoskeleton formation and ecdysis, while magnesium

is involved in enzymatic functions and osmotic homeostasis (Juniarti

et al., 2022). The importance of a balanced ionic ratio has been

emphasized in multiple studies, including Galkanda-Arachchige et

al. (2020), who reported signicant improvements in weight gain and

survival of L. vannamei when magnesium levels were adjusted in the

culture medium.

On the other hand, despite the overall trend of increasing length

and weight, body length did not always show signicant dierences

at certain sampling points (e.g., day 28), which may be attributed to

density-related factors or dierential physiological responses to the

type and concentration of supplemented ions. In this context, authors

such as Amir et al. (2021) observed that longitudinal growth may be

more strongly inuenced by specic factors such as the calcium-to-

phosphorus ratio or bicarbonate prole, whereas weight gain appears

to respond more directly to dietary mineral supplementation. These

ndings reinforce the notion that growth in nursery systems under

low salinity conditions is highly dependent on ionic bioavailability

and well-designed nutritional strategies.

Furthermore, treatment T0, which used seawater (34 ppt),

exhibited the highest specic growth rate (1.03 %), reecting the

natural ionic balance advantage provided by the marine environment

(F=2.67; p<0.05). However, treatment T2, which included dietary

supplementation with 0.2 mg.L

-1

of Ca²⁺, 2.2 mg.L

-1

of Mg²⁺, and 0.8

mg.L

-1

of K⁺, achieved a growth rate of 0.91 %, closely approaching

that of the marine control. This suggests that proper mineral

formulation can partially compensate for the ionic deciencies of

well water (Amir et al. 2021).

These ndings are consistent with Galkanda-Arachchige et al.

(2020), who demonstrated that adequate concentrations of Mg²⁺ in

low-salinity water signicantly improved growth and feed conversion

eciency in shrimp. Studies as Amir et al. (2021), reported that dietary

inclusion of mineral salts and phosphorus for L. vannamei reared in

brackish water increased average body weight and survival while

reducing FCR—observations that align with our results. Treatment

T3, which received the highest supplementation levels (0.4 mg.L

-1

Ca²⁺,

4.2 mg.L

-1

Mg²⁺ and 1.4 mg.L

-1

K⁺), showed slightly lower growth

(0.83 %) than T2 but achieved the highest survival rate (94.5 %),

suggesting that this combination may modulate physiological stress-

resistance mechanisms, even if it does not maximize growth.

Regarding feed conversion, T1 exhibited the best FCR (1.027),

despite having the lowest growth rate (0.68 %). This outcome could

be explained by a lower metabolic rate associated with reduced

mineral inclusion, resulting in a decoupling between intake and

biomass gain. Studies such as those by Ordoñez-Iglesias et al. (2024)

and Valenzuela-Madrigal et al. (2017) have also emphasized that

a well-balanced ionic prole in the diet not only improves nutrient

digestibility and metabolism but also contributes to osmotic stability

and the prevention of morphophysiological disorders during the

nursery phase. In this context, treatment T3 represents a promising

compromise between feed eciency, growth performance, and

survival, serving as a model for inland shrimp farming systems using

low-ionic well water.

Conclusions

Dietary supplementation with essential ions (Ca²⁺, Mg²⁺, and

K⁺) in pre-nursery systems of Penaeus vannamei using well water

signicantly improves shrimp growth and survival. The treatment

with the highest ionic dosage (T3) achieved a survival rate of 94.5

% and a favorable feed conversion ratio (FCR = 1.091), indicating

that the addition of these minerals to the diet can compensate for

the ionic deciencies of well water. This strategy represents a viable

alternative to optimize production in inland aquaculture systems with

ionic limitations.

The survival of P. vannamei juveniles was higher in T1 being the

best with 100 % because the juveniles did not go through high stress,

since they were kept all the time in salt water (33 ppt), followed by T3

with 94.5 % survival thanks to the greater amount of ions available in

the food, which allowed their stress to not be very high allowing the

juveniles not to be greatly aected by the ionic imbalance present in

the well water of the culture, thus ensuring greater survival, being the

opposite in T1 and T2 that obtained survival rates of 51 % and 60 %

respectively due to having lower amounts of Ca

, Mg

and K

ions.

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