
Tetras do best in a well-planted aquarium with moderate lighting using dark substrate to display their vibrant colorations. In many species, male tetras claim small territory which they defend against other males, but this leads to the liveliness of the aquarium.
Good tankmates for smaller tetras include rasboras, dwarf cichlids, corydoras, hatchetfish, pencilfish, and plecos. Larger tetras such as Bleeding Heart Tetras, Diamond Tetras and Congo Tetras can be kept with larger fish such as Angelfish and Discus. Species such as the cardinal tetras are among the most popular of all freshwater fish, adding a touch of brilliance and social interaction to the community aquarium.
In some species, sexing is quite easy. Adult females are more full bodied and wider in the stomach area, whereas, males are slimmer, sometimes having larger dorsal fin, and coloration is usually more intense. Males are often territorial and will defend their space against their neighbors by presenting themselves in profile with the dorsal and anal fins fully extended, and their coloration intensified, making the edging of the body patch stand out prominently. This is a wonderful display when it happens. Sometimes they will exchange blows which can tear the fins, but this damage heals quickly.
Most tetras are not easily breed. The Aquarist must be willing to spend a lot of time and have patience to breed them. The tetras do not engage in any type of brood care, but simply deposit their eggs on plants or scatter them around the tank. Water conditions must be very soft and acidic with a separate breeding tank for this purpose. Once the eggs are laid the parents must be removed or they will eat the eggs. The finest of food must be available for the fry, and in some species baby brine shrimp is even too large for the first couple of days. Although difficult to do, breeding the freshwater tropical fish is not impossible and can be one of the best experiences in your hobby.