Nutrients from fish or nutrition for fish: Unravelling hidden pollution risk and nutrient retention in fishponds by fish nutritional bioenergetics

Principal investigator: Jan Mráz (FROV JU)
Coinvestigator from the Department: Jaroslav Vrba
Funding provider: Czech Science Foundation
Grant no.: GAČR 22-18597S
Duration: 2022 - 2024

Link to project presentation on Czech Science Foundation webpages.

Project goals:
To understand: 1) nutritional intricacies and bioenergetics of carp in fishponds; 2) nutrient retention-excretion of fish and nutrient sequestration-emission in fishponds under dynamically changing balance of nutrition and RUE (natural + supplemental feed available to fish) through vegetation season.

Project description:
Czech fishponds currently represent rather hypertrophic, turbid ecosystems resembling a high-density fish (carp) scenario. Fish may act as a source of readily available nutrient to the environment or excavate nutrients from the ecosystem. Carp nutrition research is among the strongest pillars in fish nutrition knowledgebase. It has seldom been used as a lens to look at water pollution problems. Seasonally shifting diet scenarios may have implications on carp nutritional bioenergetics. Through digestibility-metabolic losses-retention experiments using semi-purified research diets and/or mimicked fishpond diets or direct field experiments, we intend to unravel how carps aggravate or suppress retentions (and excretions) based on different molecular (organic molecules containing N, P) stoichiometry despite same N:P, bioavailable P homeostasis, non-protein energy:protein balance, bioavailable P:protein (N) quality balances, synergistic contribution of natural food, adverse environmental conditions with changing gut food stoichiometry, anti-nutritional factors of terrestrial feedstuffs.