Stocking Density

Stocking density may negatively affect health and welfare. However, this area is complex and depends on many interrelated factors, the mechanisms of which are only partly understood. Behaviour and water quality are important elements in this specificity. High stocking densities are known to reduce growth and increase stress levels, resulting in possible infections and disease. High stocking rates may also constrain swimming behaviour. Understanding such behaviour is therefore important in maintaining rainbowfishes successfully.

Unfortunately, people who commence keeping aquaria are usually too anxious to have as many fish as possible, and most of the problems which overtake their endeavour arise from such over-stocking. Large numbers of fish confined in the relatively small space of the aquarium can often lead to impaired growth and health conditions, and before long it ends in death. This is due to reduced oxygen levels and increased toxic substances such as ammonia and nitrite. What follows is that many enthusiastic beginners become so thoroughly depressed by their first mistake that they never try again! There is one sure guidance to a beginner in these matters - have too few animals rather than too many. Most important of all, do not add too many fish to the aquarium at the same time.

Although there are numerous mathematical formulas to calculate the fish holding capacities of aquariums, they are essentially without merit. The maintenance of water quality is the best method to determine the true carrying capacity of the aquarium. Start with a very small number of fish and check the water quality using test kits for ammonia, nitrite, and pH. More fish can be added gradually, building up over the months as your aquarium matures, as long as the water quality is not diminished. Ultimately, your own observations and test results should help you determine what is a safe number of fish for your particular situation. The hobbyist who undertakes a regular program of water changes and maintenance will be able to successfully keep and maintain larger aquarium populations than those who are unable or unwilling, to perform such activities. The more fish you have, the more water changes will be needed. Each hobbyist must determine for themselves the level of effort they are willing to spend on their fish tanks and adjust the fish population accordingly. This will result in both healthier fish and greater enjoyment for the hobbyist.