Читать книгу Clinical Guide to Fish Medicine - Группа авторов - Страница 158

Most wild fish consume a varied diet that changes with location, season, and life stage. Variation of items fed to managed fish is recommended to minimize the risk of deficiencies. Additional vitamin and/or mineral supplementation may be used to compensate for potential dietary deficiencies and loss of nutrients during food storage and thawing and from leaching once in water. Many commercial supplements are available for fish, with combinations of vitamins, minerals, and fatty acids. The delivery methods range from liquids added to the water or used to soak foods, to capsules or tablets that are added to the food.

Liquid supplements can leach away before consumption, be removed by filtration, and/or negatively impact water quality. It is also hard to control the supplement dose. The efficacy of this type of delivery system for supplements is largely untested. In general, capsules or tablets are more reliable than liquid supplements. Elasmobranchs are routinely supplemented with a multivitamin and mineral tablet within their seafood, and several commercial multivitamins are available, e.g. Mazuri® Shark and Ray II tabs, Sea Tabs® for Birds, Turtles, Fish and Sharks, Vetafarm® Elasmo Tabs, International Zoo Vet Group Elasmobranch Tablets (Janse 2003; Hoopes 2017).

Since many essential vitamins are unstable in the presence of light, heat, oxygen and/or water (e.g. A, B1, C, and E), careful storage of supplements is important (Lešková et al. 2006). Independent nutritional testing is recommended to validate product labels and storage conditions. Regular evaluations of supplementation are suggested as animals, diets, and the information available change over time.

Feeding a portion of the total diet as high‐quality pellet, flake, or gel may help ensure delivery of vitamins and minerals, since these products are often formulated using water‐ and heat‐stable vitamin and mineral mixtures. This is particularly useful in species that are small and/or where it is difficult to deliver supplementation in tablet form.