Читать книгу Clinical Guide to Fish Medicine - Группа авторов - Страница 171

Fish primarily detect food through olfaction and sight; however, appearance, feel, and taste are key factors in determining whether food will be consumed (Lall and Tibbetts 2009). Compounds present in the diet may act as feeding‐stimulants or deterrents and will determine whether a food item is consumed or rejected.

Certain compounds in poor‐quality feeds are known deterrents, including highly oxidized oils, trimethylamine (produced in decaying fish flesh), and aflatoxins (produced by molds). Improper storage leading to rancidity or mold growth depresses feed intake and can result in death if consumed in significant amounts (Lall and Tibbetts 2009).

Amino acids appear to be important feeding stimulants for fish. In omnivorous fish, betaine, glycine, alanine, and mixtures of L‐amino acids are important feeding stimulants (Lall and Tibbetts 2009). In the herbivorous redbelly tilapia (Tilapia zillii), glutamic acid, aspartic acid, serine, and lysine are major feeding stimulants (Johnsen and Adams 1986; Adams et al. 1988). However, adding these stimulatory materials to the food has had limited practical success (Adams et al. 1988). The best practice to stimulate fish to feed is to deliver food types similar to the wild diet. For example, the feeding stimulants identified for redbelly tilapia are abundant in romaine lettuce.

Various supplements and medications have been used to encourage feeding within the hobbyist, zoo, and aquarium communities. These have included vitamin B/C/E, garlic, diazepam, mirtazapine, megestrol acetate, low‐dose dexamethasone, dronabinol, capromorelin, and levothyroxine. However, the supporting literature is scarce and anecdotal reports have shown that these supplements are largely ineffective. Of these, garlic shows the most potential, although high doses can lead to oxidative damage (Ashdown and Violetta 2004; Lee and Gao 2012).