Breeding

The breeding of tropical fish is probably the most rewarding part of fishkeeping and about which many books have been written. The breeding habits of fish are many and varied. They can be live-bearers (viviparous), that is, they give birth to live fry, or they can be egg-layers. The egg-laying (oviparous) fish can be separated into various groups: egg hiders, egg guarders, bubble nesters or egg scatterers.

For the beginner, the live bearers are the easiest to breed. The number of fry can vary from ten to a hundred, depending on the size of the female. Some easy fish to breed are guppies, mollies and platys.

When considering the large number of fry produced, the novice aquarist has visions of his tank becoming densely populated in a very short time, but alas, this is not so. Unfortunately, the fry make excellent food and are quickly consumed, often by their parents, unless protection is given. An apparatus designed to protect the fry can be purchased and is known as a breeding trap. It usually consists of a small plastic container that is clipped to the inside of the tank and into which the female is placed. The base has a grille through which the fry can go but the female cannot. She is then prevented from eating them. Since this device is unnatural, it cannot be recommended.

It is far better to use a separate aquarium for breeding, planting it heavily to provide refuge for the newly born fish. The mother fish can then be returned to the main aquarium to recuperate after a day or two, and the young fish allowed to grow in comparative safety.

A separate breeding aquarium is essential for egglayers, the bottom being covered with a shallow layer of very course gravel; as the eggs are laid, they fall between the grains of gravel where the parent cannot reach them. Some fish, like the angel fish, lay adhesive eggs carefully on the leaves of large plants. When the eggs hatch out, the parents watch over the fry and protect them from danger, often until they are a month or more old.

Water temperature is very important in breeding tanks and unless you have the correct breeding temperature, and can maintain it to within a couple of degrees, you are unlikely to achieve success in breeding, even though all the other factors are ideal. A proper fish room can be a definite advantage as it permits you to have several tanks which can be maintained at varying temperatures and the results of breeding in each tank can be observed and recorded. If the outside lighting is kept very dim and the walls painted black, it serves to limit the fishs' view to within the aquarium and outside distractions are kept to a minimum. Breeders who have taken this trouble report improved results.

In aquaria, spawning is not restricted to certain times of the year as in natural conditions. This is because we are able to maintain a fairly constant temperature and the seasons are indistinguishable, one from another.

In some livebearers, the females may show some changes in coloration which gives an indication that spawning is about to take place. Certainly, they become fatter due to the increase in the size of the ovaries. The males, when ready to spawn, show a more marked color change and this acts as a visual sign to the females. Males that are ready to spawn become more aggressive towards other males that show the same breeding coloration.

When spawning takes place, the majority of species release their eggs into the water where they are fertilized by sperms from the male. After this, they are at the mercy of other fish, including the parents, who frequently consume them. Some fish species do not neglect the eggs but the male, or the female, may stand guard over them until they hatch. This protection of the eggs seems to be connected with the number of eggs laid. The incidence of egg guarding is high among those species that lay eggs that are few in number. In some special cases, for example with cichlids of the genus Haplochromis, the eggs are sucked into the females mouth after laying and are then fertilized. The young brood is not released until they are able to swim and they then return to their mothers mouth for protection, if needed

In livebearers, (viviparous), the eggs are fertilized within the body and develop in the ovarian cavity. The sperms which fertilize the eggs are released by the male through the gonopodium and travel up the oviduct of the female. The young are released as free swimming fry, which are soon able to find their own food.

The size of the breeding tank has a bearing on the number of fry a fish will successfully raise and on the number of eggs that the female will lay. A large tank will produce the best results. It is in the breading tank that the importance of getting the correct pH and hardness is most essential. Some tropical fish hobbyists have a healthy, well stocked aquarium and yet they take very little trouble to secure the right water conditions. Their tanks are none the less beautiful and their fish seem to survive, but they seldom achieve the breeding results gained by aquarists who do take the trouble to provide exactly the right water conditions.

After deciding on the type of fish you wish to breed, you should make a thorough study of all the relevant literature available.

Complete Introduction to Breeding Aquarium Fishes