Fish farming, or more technically known as aquaculture, can take a number of forms, in the same way that poultry farming, or crop farming can have many forms.
Regardless of the form it takes, because it is so intensive, with many animals of the same species filling the same space, special attention needs to be paid to the management of the operation, to ensure that the fish can thrive and grow. This includes monitoring water quality to ensure that pathogens cannot develop, as well as water temperature. And, the feeding regimen needs to be carefully controlled, so that the fish receive the optimal amount ~ neither too much nor too little ~ of the correct balance of nutrients, minerals etc, to enable them to grow.
But, equally as important as the day-to-day management is to have a clear and well thought out business plan, which should include all aspects of the operation, from design and set-up right through to marketing, sales and distribution.
Fortunately, there are specialists with many years’ experience available to consult and assist in the process and costing, and who will mentor one through the initial construction and set-up stages. Some even provide formal accredited training both in the management of the operation, as well as in the day to day operations.
Rainbow trout fish farming
Despite the current controversy over whether it should be declared an invasive alien species, rainbow trout (Oncorhynchus mykiss) (pictured above) is a high value product, certainly not destined for mass consumption, but much sought-after by discerning chefs and restaurants.
To grow optimally trout prefers cooler, clear running water so is ideally farmed in lined ponds dug out of sloping ground, where a downhill flow from one pond to another will reduce the need for pumping to simply moving water from the lowest pond through a filter and back up to the highest.
In some areas it may also be necessary to cover the ponds with a light bird netting to prevent losses of fingerlings and young fish to predators.
Tilapia fish farming
Becoming more popular as a source of high-value protein, particularly among immigrants who are familiar with them in their home countries, is tilapia, of which Mozambique tilapia, Oreochromis mossambicus (or Blue Kurper, to give it its common South African name) is the most common.
Grown to commercial size, tilapia results in a soft white fillet with a delicate flavour not unlike filleted sole or perch that can be prepared in a number of ways into a delicious, nutritious meal.
While its natural habitat is rivers and streams throughout East and southern Africa as far south as the Bushmans River, it is now endangered in some of its natural area by a close relative, the Nile tilapia.
Under fish farming conditions, however, Mozambique tilapia can thrive, being a vigorous grower and quite hardy if properly managed.
And, its popularity among the wider public is growing, with it now appearing more frequently in supermarket freezers.
An alternative to tilapia which is also popular among aquaculturists is catfish, notably sharptooth catfish (Clarias gariepinus), sometimes commonly called a barbel, a hardy, air-breathing species that can grow to a harvestable size (1kg) within six months, and double that within eight.
It is a warm water species that, because it is air breathing, does not deplete oxygen levels in the water in order to survive, and can thus be grown at very high stocking densities.
Like tilapia, catfish flesh is soft and bone-free, with a mild not-overly fishy flavour, meaning that it can be used in many prepared recipes for, eg, sausage, burgers etc.
Catfish, sadly, has a poor image among consumers and while it does indeed have barbels around its mouth it should not be confused with a true barbel, which is a scaly freshwater fish of a completely different genus. The skin of the sharptooth catfish is scale-free.
Another aquaculture alternative is to set up a hatchery, taking spawn of one’s chosen species, hatching them under ideal conditions, and selling the fingerlings to farmers who will grow them on to commercially harvestable size.
A true catfish, however, is not to be confused with an internet catfish ~ someone who pretends to be someone else on the internet. This term (now officially defined as such by the Oxford Dictionary, in addition to its traditional definition as a species of fish) came about in the early 2010s when a young New Yorker documented his attempts to locate the woman he had been speaking to (and fallen in love with) on the internet. His journey took him to a ranch in Michigan where he met not the 19-year old he thought he had been talking to but a woman in her late forties who had been pretending to be someone else.
The woman’s husband told the documentary makers a story of Alaskan fishermen who, when transporting cod in large vats on ships to China, found the cod arrived mushy and tasteless. So, they hatched a plan to throw a few catfish into the vats with the cod to chase the cod around, nipping at their fins to keep them moving. The woman’s husband finished off by saying he is thankful for life’s catfish, because if we didn’t have someone chasing us around life would be dull and boring. And that’s the story of how internet catfish got their name.
This is part two in a series on Dams & Fish. For more, click here.