Learn Freshwater Aquaculture
Introduction To Aquaculture
Production Systems - EP and IP
What Species To Farm
Setting Up A Fish Farm
Fish Foods & Feeding
There are three main species of trout farmed: rainbow trout (Onchorrhyncus mykiss), brown trout (S.trutta) and brook trout (Salvelinus fontinalis). Of the three, rainbow trout have adapted to warm conditions the best.
Rainbow trout is native to the rivers draining West North America, from Alaska to Mexico. It has been cultivated as an introduced species for recreational and food production purposes since 1874. Its culture has boomed since pellets feeding started in the 50’s, even in warm water countries from tropical and subtropical areas of the world. Rainbow trout were exported from Scotland to Africa in 1897 and successfully raised and bred at a number of hatcheries thereafter. For many years they were stocked in rivers, streams, lakes and dams for angling purposes only – i.e.: they were not commercially farmed for human consumption. Nevertheless, today there are quite a few waters where suitable living and breeding conditions exist and trout are well established and these populations self perpetuating.
It is only in recent decades that the importance of trout as an agricultural product has been realized and exploited in some countries.
Because environmental conditions are generally not suited to trout they are not found in great numbers in nature in warm countries, as are bass, tilapia, catfish and many other fish tropical and subtropical species. Trout are best spawned in a hatchery and the eggs and young cared for under controlled conditions.
The hatchery cannot be left to run itself for very long and needs attention every day. Fish need to be fed regularly, they need to be sorted to reduce bullying, water quality needs to be monitored, water filters cleaned regularly and fish checked for diseases and parasites, to name just a few of the more important regular checks.
During the breeding season a large number of man hours are usually needed for netting, spawning and looking after the young fish. However, the amount of labour and man hours depends on the system of collecting and spawning the fish that is used. Also, the larger the operation the more labour is needed.
Many hatcheries carry stocks of large, breeding fish to give them a sufficient supply of ova during the spawning season. This requires pond space throughout the year to hold the fish, feeding, water and labour. Sometimes these ponds need protection against poaching and natural predators, ie birds, otters, feral cats, etc.
Some farms are for spawning of trout only. The fish are spawned, the ova grown to eyed stage and then sold. No hatching or growing on is done except for selected fish used to replenish the breeding stocks. This makes allowance for the specialist growing on farm. These latter farms can buy in ova and hatch and grow the fish to a marketable size. There is also the third type of trout farm those that do both breeding and growing on.
Trout farming is determined by several factors that affect water: quality, temperature and dissolved oxygen.