Aquarium Problems
The three hazards that most tropical fish face are overcrowding, overfeeding, and temperature change. Overcrowding exists when there are more fish in the tank than it can support. It has been found that there is hardly ever a shortage of oxygen dissolved in aquarium water but that there may develop an excess of suffocating carbon dioxide. When fish are too crowded, the concentration of this gas reaches lethal proportions.
The safest formula for spacing your fish, therefore, is to allow 1 gallon of water for every inch of fish. If you have ten small fish that average one-half inch in length, then you can safely keep them in a 5-gallon tank.
The water gives off carbon dioxide to the atmosphere at its surface; thus the surface area of the tank is another important factor in determining the number of fish that you may safely maintain in your aquarium. The larger the surface area, the more chance for the carbon dioxide to escape into the atmosphere. One of the dangers of a spherical or globe type of tank is that it has a small neck and not much carbon dioxide can be discharged by the water. To be safe, figure on a minimum of 10 square inches of surface area for every inch of fish. Using a proper filter and air pump can greatly enhance the capacity of your aquarium. While 10 square inches of surface for every inch of fish is acceptable for un-aerated aquaria, sufficient aeration and water changing on a regular basis can easily allow you to have four times that many fish. But don't overcrowd! Instead, buy a larger aquarium...or smaller fish.
Then, too, there are other considerations about the density of fish in a given aquarium. Many fish, especially cichlids, are extremely territorial and they may fight off any fish that comes into what they consider their territory. African Great Lake cichlids are almost always territorial and not more than one pair of adults can be kept for any length of time in any tank under 10 gallons...and even that is a bit small.
These precautions should be taken into consideration before you buy your tank.
