Animal Husbandry is defined as, ” The branch of agriculture concerned with the care and breeding of domestic animals such as cattle, hogs, sheep, and horses.” I am sure that it could quite easily be applied to the breeding of fish and in my case, specifically Tilapia.
An interesting definition of Aquaculture on the other hand can be found over at the State of Maine, Department of Marine Resources. They end their definition with this sentence, “In order to qualify as aquaculture a project must involve affirmative action by the lessee to improve the growth rate or quality of the marine organism.”
Now for my South African readers this reference to “affirmative action” does not mean our quaint local custom of firing perfectly competent white workers and replacing them with random (or politically connected) appointees solely on the basis of their skin colour to earn BEE points, but rather the direct intervention of the aquaculturists to protect, nurture and grow the fish under his care. This intervention takes the form of feeding, heating/cooling, treating disease and ensuring water quality and filtration.
Another really important form of “affirmative action” takes place during the breeding process. Like many other animals, fish do not make particularly good parents. Or at least they don’t appear to. It is difficult to judge the actions of a fish living in a totally artificial environment, so I am prepared to give them the benefit of the doubt. My experience however, over a five-year period actively breeding Tilapia is that I can achieve survival rates thousands of times more successful than the parents, if left to their own devices.
The intervention in the breeding process of Tilapia entails either stripping eggs from the mouths of the females and then hatching them in an incubator or allowing the female to hatch the eggs and then removing the fry immediately they are free-swimming. Over the years I have tended towards the latter approach because despite the yield being marginally lower, the effort and cost entailed is substantially less.
Which brings me back to Animal Husbandry and the merits (or demerits) thereof. Two weekends ago, while cleaning the Tilapia tanks in my home AP system, I had cause to really question the logic behind saving the life of a baby fish when, if no intervention was made, it would have most certainly been eaten by its parents.
To perform my annual “deep clean” of my tanks, I move all the brood fish into one tank, drain the other and then spend 3-4 hours scrubbing the sides and bottom of the tank until it is as clean as new. Moving brood fish in the middle of breeding season is sure to result in thousands of coughed up fry, egg-sac fry and unhatched eggs. We have had a particularly good breeding season so I was prepared to make this sacrifice and we save as many of these as we can while the clean takes place. Once this tank is cleaned, the tank is filled, the fish are all moved to the clean tank and the process is repeated in tank #2. More eggs and fry are spat out and we get busy with the net again.
I have always told my clients that Tilapia, being vegetarian, are not particularly interested in eating their young. I have seen a female accidentally “swallow” her entire brood when stressed, but I cannot say that I had seen them actively eat their young. That was until now.
While busy in the second tank, I peeped over the rim and looked into the clean tank. A school of a couple of hundred Tilapia fry were swimming around the edge. The net was nowhere near at hand so I chose just to observe. A large male of about 800g slowly swam up to the school and gently opened his mouth and “sucked” in about 50 at a time. He swallowed and then repeated the procedure until there was only about 10 little fish frantically darting out of his reach. These I rescued later and moved to the fry tank.
Which got me thinking. These rescued fish were faster and more alert than their eaten siblings. Had I unwittingly stumbled on a “survival of the fittest” and “natural selection” exercise in progress. By practising Animal Husbandry are we not saving fish and their inferior attributes that would not have stood a chance in nature? And it’s not just fish. By feeding, protecting and healing animals, are we not breeding progressively weaker and inferior animals?
It is easy to criticise these “dumb fish” for eating their young, but are they not in fact ensuring that only the fittest, strongest and quickest babies make the next generation and in turn stand a better chance against real predators in nature?
I felt rather humbled by this observation.