Jun Jun was given an aquarium by his dad for his birthday. It was a twenty gallon glass tank with goldfishes. Every week, Jun Jun would go to the petshop to buy a fish and add it to the aquarium. And he was happy with his aquarium until he noticed that one day the fishes look stressed - they swim listlessly and went to surface. Jun Jun was stressed. Within a few hours all the fishes died. Jun Jun was sad and the fishes were dead.
WHAT HAPPENED?
An aquarium is a complex thing. Too many fishes were added and probably too many fish food were placed in that destroyed the water quality, making the tank water poisonous … toxic … or lethal to the fishes. One thing was sure though the water was compromised the quality of the water reached lethal levels leading to fish kill in the aquarium.
Jun Jun was sad but he learned his lesson and for a week read books on aquarium keeping and talked to more experienced hobbyists. And this was what he should have done even before otherwise his fishes would still be alive.
Jun Jun learned his lesson.
Now what is the difference between keeping an aquarium or keeping a pond or even keeping a fish cage in a lake? Nothing much except size. The same factors that affect the survival of an organism in an aquarium affect also the fishes in a pond or in a lake and in the sea,
WATER QUALITY: THE QUALITY OF LIFE
Whenever we look at the quality of Life in terms of the physical, chemical and biological aspects we always say FRESH. As in fresh air and fresh scenery. What this means we have adequate and more adequate supply of oxygen, clean water and a host of other things. Scientifically a good living environment is best describe in the levels of oxygen, carbon dioxide and other similar things as being in the optimum or just right level. If ever there is a deviation the aquarium suffers.
An aquaculture (the science and sometimes art of keeping, breeding and raising aquatic plants and animals in a body of water) manual points to man as the fulcrum or plays an important role in the balance of physical, chemical and biological levels of an aquarium, pond or even a fish cage.
HOW DOES WATER QUALITY DETERIORATE?
Waste, waste from the fish and waste from the uneaten food lowers water quality. Toxic compounds like ammonia, nitrate and nitrate are formed. The levels of dissolved oxygen goes down. The fishes become stressed and then the level of dissolved oxygen goes down further. Without water change or change in the feeding or in stocking fishes the degradation of water quality goes on its merry path until all become toxic and then is as if the poison was placed in the water, leading to mass killing of the fishes.
In an aquaculture there are three ways of keeping or culturing fishes based on stocking - extensive, medium and intensive. Extensive puts the least amount of fishes per gallon or per meter and intensive the most. Needless to say since the extensive has the most amount of space for the fish it needs less equipment and management to keep the water quality at a the optimum level. Intensive culture on the other needs more equipment and more management to keep things at optimum.
Even factors beyond the control of the owner and keeper of the aquarium, pond or cages can be prepared for. Again based on its stocking density the intensive is the most vulnerable, the most prone to have fish deaths and fish kills.
For Aquaculture a fish cage is the most practical since ideally the waste does not stay inside the cage and the flow of water gives it a steady supply of water. However, overtime the cages does have an affect. One of the effects would be the lake depth would decrease - it becomes shallower. Another possible effects would be the increase in the amount of organic waste - from the fish and the uneaten fish food - in the lake. Leading to the prime or major effect of worsening the water quality - which if it would not kill the fishes (and possibly other organisms) would with certainty make its inhabitants - fishes and other aquatic organisms - vulnerable or open to attack when there is sudden change in physical and chemical quality of the water.
Hence the fish kills.
Jun Jun learned his lesson.
Have we ?