• Breeding freshwater aquarium fish

Goldfish
Goldfish are generally easy to breed! They are a very social animal and do well when kept in groups.
Goldfish typically shoal, forage and feed in groups and are likely to breed as well. It is best to add oxygenating plants such as Anacharis in the aquarium for the spawning process and for eggs to adhere to.

To induce spawning, the temperature can be slowly dropped to around 11° C (60° F ) and then slowly warmed until they spawn. This is done to mimic the conditions found in nature when spring arrives which is the only time they will spawn in the wild. Feeding lots of high protein food such live brine shrimp and worms during this time will also induce spawning.

Before spawning as the temperature increases, the male will chase the female, in an unaggressive way, around the aquarium. This can last for several days. The colors of both fish will intensify, the male somewhat more than the female. During spawning the male will push the female against the plants while both fish gyrate from side to side. This stimulates the female to drop tiny eggs which the male will then fertilize. The eggs will stick to the plants by sticky threads. Spawning can last 2 or three hours and can produce up to 10,000 eggs. The parents, when finished will then eat as many eggs as they can find.

For this reason it is best to remove the parents after spawning is complete. You will need to feed one of the various specialty foods for fry (see Foods for Fry) until they become big enough to eat flake or brine shrimp. At first the fry are a dark brown or black color in order to better hide and not be eaten by larger fish. They gain their adult color after several months and can be put in with larger fish once they reach about 1 inch long.

Anabantoids (Labyrinth Fish)
Most anabantoids are bubble-nest builders. The nest is built and maintained by the male. Male anabantiods will take some time to build a nest of bubbles in floating debris or plants. They entice their mates under the nest and induce them to lay their eggs by giving them a spawning embrace. The eggs are immediately fertilized and placed in the nest by the male who guards them and later, the fry against all intruders.

In the aquarium, an upturned butter dish or something similar can serve as the anchor for the nest. This is usually not necessary though if there are plenty of plants, especially floating plants like hornwort, in the aquarium. The breeding tank is usually small (5 or 10 gallons) and shallow with lots of hiding places for the female (plants and rocks). After the male and female are placed in the tank, the bubble nest is usually built within a few days.

The female can be removed after spawning because the male may become aggressive towards her. The male will then watch over the eggs until they hatch 24 to 30 hours later. The temperature should be about 80° F with a lower temperature extending the hatching time and a higher temperature decreasing it. After hatching, the fry will absorb the yolk sac in two or three days. The fry will not be large enough to eat baby brine shrimp for several days so they must be fed infusoria or cooked egg yolk squeezed through a cloth.

The larger anabantoids are easier to breed mainly because the fry are large enough to eat baby brine or pulverized flake food. For example, dwarf gouramis are harder because the fry are so small they need infusoria to survive the first week or so of life.

Catfish, Corys (Armored Catfish)
Suggested water conditions for breeding: pH: 6.0-6.5, hardness: 4° dGH. To prepare a pair for breeding set up a tank with large leafed plants. Feed the pair plenty of mosquito larvae and other live foods. Spawning is stimulated with frequent water changes.

The Corys have a very interesting breeding routine. After bumping the male on the vent, the female will receive the males sperm into her mouth. She then discharges a few eggs which she catches and clasps with her ventral fins. Then the female will swim around and deposit a bit of sperm and just a few eggs at a time in select spots, such as on the underside of a selected leaf, some will deposit them on the heater tube or ever the aquarium glass.

When the female has runs out of sperm, she will go back to the male and repeat the process until the spawn is complete. This will continue until about 100 eggs are deposited. Different species will put different amount of eggs on each leaf or other selected spots. After spawning the pair should be separated from the eggs. The eggs should be well aerated and treated to prevent fungus form growing on the eggs.

The fry will hatch after four or five days and can be fed rotifers, Artemia nauplii and the contents of fresh peas.

Cichlids
There are several different groupings that Cichlids fall into concerning breeding habits. Almost all the Cichlids are either "substratum-spawning" or "mouth brooders".
This means they either lay the eggs on some portion of the substratum, (including pits dug in the sand, leaves, and flat rocks), or they take the eggs and fry into their mouths to protect them from predators. Another, and more important distinction if you are planning to breed Cichlids, is whether they are monogamous or polygamous.

The material here is taken mostly from Dr. Paul V. Loiselles' excellent book The Cichlid Aquarium, published by Tetra Press, 1985
Monogamous cichlids pair off when allowed to interact freely in the aquarium. Therefore about six or more young fish should be purchased and grown up in the same tank. As soon as they start pairing off, separate the pairs as they will claim a territory and defend it fiercely. Pairs often have trouble because aggression results in a battered female. For this reason many breeders set up barriers in the tank that only the female can pass through thus giving her a safe place away from the male. At the very least a lot of hiding places and maybe a few target fish can be introduced to the pairs' aquarium. The idea is that aggression is taken out on the target fish rather than the female of the pair. Suitable target fish should be fast like giant danios or botias or be able to dive into the gravel like some eels and loaches.

Polygamous cichlids come in two varieties, open polygyny, where males and females consort freely among each other, and harem polygyny, where males maintain a territory with several females for an extended period of time. Harem polygyny is based on one male protecting several spawning sites from other males. The actual spawning sites are then claimed by each female within the male's larger territory. Females vigorously defend these actual spawning sites. Usually after spawning the male is no longer allowed near the spawning site and the female takes care of the eggs. This type of cichlid is usually marked by extreme sexual dimorphism, with the male being much larger and having more elaborate finnage. To breed such cichlids, you therefor need a large enough area so that the male has a place to go after spawning so the female won't batter or kill him. Fortunately most harem polygyny cichlids are dwarfs so a 20 gallon aquarium may be large enough. Overturned clay pots can serve as spawning sites and plenty of plants are always welcome even though prespawning activities may uproot them.

The biggest problem with open polygyny cichlids is that they are thought to form pairs, and being housed this way, the female almost always ends up battered or killed. To avoid this, you can either house them in a community situation with other cichlids (and thus run the risk of producing hybrids) or house a male with at least three or more females. This spreads the abuse out over all the fish which increases their chances of survival. Almost all the open polygyny cichlids are mouth brooders which means the eggs and fry are carried by the female in her buccal cavity (mouth) until they are free swimming. The substratum spawning cichlids usually excavate pits in the substrate in which to lay their eggs. In both cases the parents will defend the eggs and fry until they are free swimming.

Characins (Egglayers)
Characins, which includes Tetras, Silver Dollars, Hatchetfish, Headstanders, and Leporinus, are free spawning. This means they will discharge the eggs and sperm into the open water, though always around bushy planted areas.
Charcins all breed the same, with just a few exceptions. It is best to spawn them by separating the males and females and then feeding them heavily on live foods until the females grow fat and the males become more colorful. Then introduce a female and a male into a specially prepared spawning tank.

The spawning tank can be a low aquarium (5 gallons to 20 gallons depending on the species) filled 3/4 full with clean, aged water and lined with a dense foliage about two inches thick. The Glowlight Tetra is an exception here, in that they don't like the vegetation dense. You do not need any sand on the bottom but you can add a few pieces of wood or twigs with free space underneath to give the fry a place to attach. For the Neon Tetras, it is recommended that everything you place in the aquarim be sterilized, as well as the top. Other characins do not seem to need quite as much care to spawn successfully.

Usually an increase in temperature to about 78° F (see individual species), plenty of live foods, and covering the aquarium with a towel (to darken it and maintain temperature) will trigger spawning. Spawning usually takes place in 48 hours up to a few days. The eggs of most characins are quite sticky and will then adhere to the foliage as they are dropped. Remove the parents as soon as they have completed spawning as they will eat the eggs.

The spawning aquarium temperature can then be increased to and maintained at about 80° F . The eggs hatch quickly, usually in about 36 hours. The fry need to be fed infusoria, especially rotifers, for 1 to 4 weeks, depending on the species. Then they can eat brine shrimp.

The Congo Tetra is another exception here in that they spawn in temperatures of 77° F , and their eggs take 6 days to hatch.

Cyprinids (Egglayers)
Most Cyprinids, which includes Barbs, Danios, Rasbora, and Black-tailed sharks, are free spawning. This means they will discharge the eggs and sperm into the open water.
Usually an increase in temperature and feeding plenty of live foods will trigger spawning. The eggs will then adhere to whatever they come in contact with: leaves, decorations, gravel, etc. The eggs hatch quickly, usually within 30 hours at which time the fry can eat finely powdered flake food followed by baby brine shrimp after a week or so.

The parents will eat the eggs and the fry so some means of protecting the eggs is needed. To accomplish this you can use spawning grass, marbles in the bottom of the aquarium, or a grating that the eggs can fall through but the parents cannot. After spawning it is a good idea to remove the parents.

One of the notable exceptions to this method of breeding is the practice of the Bitterling, Rhodeus sericeus amarus, who protects the eggs within the Mussel and defends them after they have hatched.
* See the freshwater plants: Anacharis and Hornwort