ZeEfficacy – Efficacy Services


Diet studies

These studies are aimed at food manufacturers or nutraceutical companies, as well as farm and veterinary industries interested in testing the properties of certain diet components on the physiological status of adult animals.

Our diet studies provide animal food manufacturers with a way to evaluate the impact of dietary effects on adult animal fitness, animal growth, and reproduction. We have recently developed metric studies of the effects of custom diets or food supplements on the physiology of adult zebrafish. Parameters affecting metabolic aspects, gonad development, reproductive success, growth, and weight gain can be evaluated according to your needs.

We can also address food and nutraceutical industry needs by testing the safety of new food additives or preservatives for human consumption, as well as the health benefits and safety of nutraceutical products.

Diet studies

Dietary zebrafish models for the study of adult general physiology and fitness.


  • Evaluation of general physiological status, metabolism, and fertility in adult fish challenged with a specific diet, food additive, or supplement.
  • Tailored comparison of diets versus the current market leader.
  • Screening of diets or dietary supplements that can enhance reproductive capacity, improve length and weight (gain muscular tissue), or any other physiological aspect.


Zebrafish have highly conserved physiology with vertebrates. They share cell types, metabolic pathways, and organ functions, thus providing biologically relevant readouts.

Fast and cost-effective assay to test diet effects.

Two-phased studies, in larvae and juvenile fish are evaluated the metabolic readouts and in adult animals adds fitness parameters.

Method description

21 days post fertilization (dpf) zebrafish are fed on each diet of interest and compared to the formulated reference diet (control diet) for 16 weeks. Before starting the diet protocol, a subsample of zebrafish in each group is weighted and measured to obtain initial weights and lengths. Diet groups are daily fed with not less than 5% body weight (divided into 2 feedings), which are adjusted for growth periodically. At the end of the protocol, each individual is analyzed by evaluating several readouts.


  • Development and performance evaluation
    • Mortality: every two weeks.
    • Body length: every two weeks.
    • Body weight: every two weeks.
    • Specific Growth Rate (SGR): at the end of the study.
    • Body Mass Index (BMI): at the end of the study.
  • Reproductive capacity evaluation
    • Fertility rate: after development and performance evaluation, zebrafish are sexed and crossed several times at sequential time points to evaluate the fertility rate under the same husbandry conditions and diet regime as for the 16-week experimental phase.
    • Number of successful breeding events
    • Number of eggs laid
    • Number of eggs hatched and viable embryos
    • Sex ratio
  • Glycemia evaluation
    • Blood glucose levels: fasting blood glucose levels are evaluated through a standard glucose kit in some males and some females.
  • Gonad size evaluation
    • Gonadosomatic Index (GSI): some males and some females of each condition are dissected and gonads are weighted.
  • Liver evaluation
    • Liver steatosis: some males and some females are processed with specific lipid staining for evaluating liver fat accumulation.
Figure 1. Comparison of diets versus the current market leader in terms of development and performance. A) Weight and B) length are two typical readouts used to evaluate adult animal fitness. In this example, the reference diet is better than the study diet (diet 1).
Figure 2. Comparison of diets versus the current market leader in terms of A) gonad size and B) reproductive capacity. In this example, fish fed with the reference diet show larger gonad size and produce a higher amount of eggs per spawn than the study diet (diet 1).

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studies or have any other questions,
please contact our experts.