Basics: Stocking rate for fish

As I was doing my daily surfing of the blogosphere I came across Dean's adventure with a guppy in fishbowl. After posting what I hope are helpful comments I immediately remembered this blog. This has to be my most neglected blog. So catalysed by the lack of attention this blog has been getting I resolved to do something about it. I will talk about stocking rates. Or how to stock the correct number of fishes in the tank.

A great majority of fish deaths and aquarium ecological collapse is due to overstocking. This is one of the downsides of the over-eagerness in the aquarium keeper to add more fish. The other being adding a belligerent or predator fish in a community tank will give the aquarium a uber-dynamic quality to it that will eventually result in a solitary fish occupying the tank.

Stocking rates, number of fish or total length of fish combined that can be placed in the tank, is dependent on:

On the type of fish - Is it a saltwater (SW), freshwater (FW) or brackish water (BW) fish? What type of fish is it? How big does it get?

Stocking rate differs between a salwater and freshwater fish. I generally use 3 to 6 gallons per inch of total fish length for FW fish and 10 gallons per inch for total fish length of SW and BW fish. The reason for this is because SW fishes are more sensitive to environmental changes and require more stable environment, one way to achieve this is to increase the volume of water or living space for the fish. For FW there is also a 3 gallon difference mainly because one should take into consideration not only the fishes length but also its girth, please note as Dr Seuss said fishes come in different sizes and shapes and this should be taken into account. Always remember to check the adult size of the fish in order to find out how many fishes one can keep. Also remember to check fish books/atlases and visit aquarium websites to find out more about your prospective fish or aquarium pet before introducing it into your aquarium.

Stocking or keeping a number of fishes in an aquarium can be done in three ways. Extensive, semi-intensive and intensive. These are all fishery term describing the number of fish in a given enclosure (aquarium). Extensive means the fish occupies more space than usual. The number of fish per gallon increases in the semi-intensive to intensive. Please note in the extensive stocking the equilibrium of the system (pond or aquarium) is maintained by changing water and proper feeding ( quick tip: usually the stomach of the fish is no bigger than its eye) while in the semi-intensive and intensive system machines are introduced to aerate the water, improving oxygen content in the water, and filters are used to clean and transform waste products to its less toxic form.

In extensive stocked aquariums equilibrium is maintained by doing water changes and introducing natural water filters, plants. This delicate equilibrium is only broken when one oversteps the ideal number or size of fish allowable in the aquarium or when the toxic waste reaches an undesirable level. One should always remember that unlike the environment of the fishes in the wild the aquarium no matter how big is a smaller and more fragile version of the fish's natural world. It is essentially a closed system that suffers from accumulation of waste brought about by neglect.

Filters and other machines are used to lessen the amount of toxic substances in the aquarium. Even with the most advance filter there is still a need to control the amount of food given and to do regular water changes.

The aquarium is really a dynamic world. A microcosm where there is a need to always maintain eqilibrium. Blame for the death of the fish and collapse of an aquarium set-up , known to some as toxic tank syndrome, rests solely on the aquarium keeper. Its actually a good tool to see what would happen if we badly managed our world. Some people call the aquarium a microcosm, a smaller version of our world.


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