Economical fish and shrimp production requires maximum nutritional efficiency from feed. Enzymes, including phytase, xylanase, cellulase, protease, lipase, and amylase increase the availability of nutrients, increase absorption of nutrients during digestion, increase fish growth rates, and assist in the survival and thriving of fish in the larval stage. Also, the use of lower cost feedstuffs is made possible for aquaculture with the use of added enzymes. Nutrients that are not digestible using the fish’s normal digestive enzymes become digestible when appropriate enzymes are added to these less expensive feedstuffs.
The use of phytase, a very popular enzyme used in fish feeds, also has environmental ramifications. Phytic acid, or phytate in its salt form, is a complex phosphate containing molecule that is found in many grains used to formulate fish feeds. The fish has no natural enzyme to break down phytates and hence does not absorb the needed phosphate nutrient but instead allows the phytate to pass out in its waste contributing to increased phosphate build up in the water. Phytase breaks down the phytate in the fish’s digestive system, allowing the phosphate to be used as a needed nutrient while simultaneously greatly diminishing the release of phosphate into the water.
Enzymes, particularly proteases, can be used to digest the waste buildup in the pond and greatly increase the clarity of the water by hydrolyzing the proteinaceous waste materials that build up. Another effective long term treatment for purifying and clarifying the pond water is to add Bacillus spores to the water. Bacillus will naturally produce enzymes that will purify and clarify the water and Bacillus will also inhibit the growth of common fish pathogens such as Aeromonas.