Abstract-based review · 2025
Whole-fat and defatted krill powder in koi diets
Growth, colour and some immune measures improved, but high inclusion groups also showed adverse liver changes.
Review scope
Abstract-based review. Full methods, complete statistical results and product equivalence have not been appraised. This is research context, not an individual feeding or treatment recommendation.
Study question and design
630 red-white koi; seven groups with three replicate tanks each. 60 days with 10%, 20% or 30% fishmeal replacement by whole-fat or defatted krill powder.
Main findings
Growth, colour and some immune measures improved, but high inclusion groups also showed adverse liver changes.
Limitations and applicability
Replacement percentages are not percentages of the entire diet. Processing form and inclusion level affected results; benefits do not remove the adverse findings.
Ingredients investigated
Direct ingredient investigations
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Defatted Antarctic krill powder replacing fish meal. Dose: 10% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Defatted Antarctic krill powder replacing fish meal. Dose: 20% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Defatted Antarctic krill powder replacing fish meal. Dose: 30% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Full-fat Antarctic krill powder replacing fish meal. Dose: 10% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Full-fat Antarctic krill powder replacing fish meal. Dose: 20% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Krill
Direct · koi. 630 red-and-white koi carp, initial weight about 13.5 g; seven diet groups with three replicate tanks of 30 fish.
Tested form: Full-fat Antarctic krill powder replacing fish meal. Dose: 30% fish-meal replacement (Replacement percentage of fish meal, not percentage of the whole diet; oral feeding). Duration: 60 days. Comparator: Fish-meal-based control diet without krill replacement.
Measured finding: The tested diets changed growth, colour and immune measures. Liver changes were also observed at high inclusion: lipid droplets with full-fat 20% and 30% replacement and adverse findings with defatted 30% replacement. The reviewed abstract does not isolate every endpoint for each arm.
Limitations: Koi-specific tank trial; whole-diet replacement comparisons. Full-fat and defatted krill are different preparations. Results do not establish effects or safe inclusion levels for every krill-containing ornamental-fish product.
Evidence.pet interpretation
Apply this result only within its species, preparation and study conditions. An ingredient listing alone does not establish that a commercial product reproduces the tested intervention.
Funding and conflicts
Not established from the reviewed abstract.
Ingredient references
These are research references. The tested form, dose and formulation must be matched before using a result to support a product claim.
Source
Song H et al. Dietary Supplementation with Whole-Fat or Defatted Antarctic Krill Powder Improves the Growth Performance, Body Coloration, and Immune Capability of Red-White Koi Carp (Cyprinus carpio var. koi). Animals. 2025. DOI: 10.3390/ani15111561.
Primary source record (PMID 40509027) · Publisher DOI
Reviewed 2 October 2026 · Next review 2 January 2027.