Why is There a Need to Supplement Enzymes in Fish Feeds?

Supplemental enzymes are essential for profitable fish farming.

Supplemental enzymes released by proprietary blends of bacteria in aquaculture help fish digest the complex carbohydrates in plant foods that help them gain weight. They keep water cleaner and reduce the substrate for pathogenic organisms.

Fish Is Vital to the Future of Food

As the human population increases, the climate becomes less predictable, and available arable land becomes increasingly scarce, fish is becoming a more and more important part of the human diet.

Fish is an excellent source of protein. A 100-gram serving of fish provides 18 to 20 grams of complete protein.

Fish does not complicate weight control. That same 100-gram serving of fish counts for just 100 to 200 kcal of energy, depending on the fat content of the fish.

Fish also provides a variety of useful minerals, and relatively rare compounds of nutritive significance, such as astaxanthin.

Fish are extraordinarily efficient converters of their feed. Depending on the species and growing conditions, fish convert 1.2 to 2.0 pounds of feed into one pound of edible fish. Compare that to the 8.7 pounds of feed needed to produce one pound of beef or the 5.4 pounds of feed per pound of edible chicken.

Wild stocks of fish are under stress in every ocean, but fish can be produced through aquaculture. The success of fish farming, however, depends on the availability of enzyme supplements as well as carefully selected feeds.

Enzymes Help Fish Digest Plant Foods

There is a very simple reason that farmed fish need supplemental enzymes:

Fish meal is expensive.

There is competition for the available supply of fish meal. Grains are far more affordable input.

Most farmed fish prefer high-protein food from marine sources, but the cost of catching the fish to make fish meal has astronomically increased. Most aquaculturists have turned to grains as supplemental feed for their stock.

Grains and coconut, however, are not a natural food source for ocean-dwelling fish. They are not inherently digestible by desirable species of fish, even if they are added to fish meals to make nutritive pellets.

Corn, corn meal, wheat bran, rice bran, ground sunflower seed, ground cottonseed, linseed meal, copra meal, and de-oiled rice bran are all potential additives to fish food.

The problem with these feed additives is that they contain a variety of problem components, including:

  • Phytic acid interferes with the absorption of minerals from animal protein.
  • Cellulose, hemicellulose, and lignin, for which fish lack the probiotic bacteria required for digestion in the gut. Cellulose, hemicellulose, and lignin increase the viscosity of fish food and accumulate as sludge in the growing area if they are not remediated.
  • Tannins and lectins, which cause immune reactions, activate enzymes in the fish liver that are needed for other digestive tasks and interfere with the absorption of nutrients.

Enzymes remedy the problems with these components of plant foods for fish.

Phytase, for instance, releases 80 percent of phosphorus in grain bound to phytate. It also releases amino acids, calcium, magnesium, zinc, copper, and iron in chemical combination with phytic acid.

Because it enables the incorporation of the phosphorus in grains and copra into the flesh of the fish, it reduces the amount of phosphorus in their fecal matter and improves water quality.

Cellulase prevents the accumulation of fiber in the growing medium. It helps keep water cleaner and removes nutrients that might otherwise support bacteria that reduce the oxygen concentration of the water.

Proteases and lipases break down the chemical bonds between non-nutritive and anti-nutritive tannins and lectins in plant foods. This allows them to be excreted with waste rather than absorbed into the fish’s circulation.

Enzymes, of course, are sensitive to heat, pH, and salinity. Even if they can be mass-produced, they cannot be dumped into open water.