7.4.4 Trout

Main commercial type:
Rainbow trout (Oncorhynchus mykiss)

FIGURE 7.10
Line drawing and photograph of a Rainbow trout (Oncorhynchus mykiss)

 

Description

Trout are carnivorous cold-water fish that belong to the salmon family (Figure 7.10). All trout require cold er water than the other species previously mentioned, preferring 10-18 °C with an optimum temperature of 15 °C. Trout are ideal for aquaponics in Nordic or temperate climate regions, especially in winter. Growth rates significantly decrease as temperatures increase above 21 °C; above this temperature trout may not be able to properly utilize DO even if available. Trout require a high protein diet compared with carp and tilapia meaning greater amounts of nitrogen in the overall nutrient pool per unit of fish feed added. This occurrence allows for more cultivable areas of leafy vegetables while maintaining a balanced aquaponic unit. Trout have a very high tolerance to salinity, and many varieties can survive in freshwater, brackish water and marine environments. Overall, trout require better water quality than tilapia or carp, particularly with regard to DO and ammonia. Successful aquaculture of trout also requires frequent water quality monitoring as well as backup systems for air and water pumps.

Rainbow trout is the most common trout species grown in aquaculture sy stems in the United States of America and Canada and in sea cages or flow-through tanks and ponds in central or northern Europe (Norway, Scotland [the United Kingdom]), in parts of South America (Chile, Peru), in many upland areas in tropical and subtropical Africa and Asia (Islamic Republic of Iran, Nepal, Japan) and Australia. Rainbow trout are long, thin and scale-less fish, usually blue-green and spotted on top with a red stripe on the sides. Trout are also cultured and released into streams and lakes to supplement sport fishing.
Trout require a high-protein diet with substantial amount of fats. Trout are considered an oily fish", a nutritional description indicating a high amount of vitamin A, vitamin D and omega-3 fatty acid, making them an excellent choice to grow for domestic consumption. Trout command higher prices in some markets for the same reason, but they require diets comparatively rich in fish oil.