Fish keepers start out with a few tropical fish or maybe some gold fish in a small aquarium. But they soon want to know more about how their fish live, and especially how they breed.
General aspects of fish breeding, just like with fish keeping, include proper feeding and providing the right environment. The breeding environment needs to be maintained with proper water conditions and you need to watch for disease or other ailments.
Some fish are easy to breed and will readily spawn in a community tank. But most fish need a bit more help. Understanding the spawning behaviors and needs for the particular type of fish will make fish breeding successful and rewarding.
Carefully selecting the "brood stock" (parent fish) and condition them on a good varied diet is important. A fish breeding tank is needed for many species as well. The breeding aquarium needs to have the right water conditions to stimulate spawning and for the eggs to hatch. Consideration also needs to be given to the fry and their survival. The first foods for the fry, before they become free swimming, and foods for the fry to grow are important. It's also important that they are protected and have places to hide.
For first timers, or those who are new to the hobby, it's advisable to start out with some of the easy to breed livebearers. These include the Guppies and Platies. Then move on to some of the hardy egg-layers, like Danios and Barbs. Experience with these initial undertakings will greatly help in keeping and breeding many other types of fish, including some of the very difficult species.Tetra-Press, 1985.
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 in groups 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 a non-aggressive 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.
Most species of Killifish are sexually dimorphic. Males are much more colorful than females and will have larger dorsal and anal fins. Having adapted to life in very diverse habitats, the Killifishes are divided into two groups based on different methods of reproduction that they employ. The first group of Killifish are those that are bottom spawners, pushing or burying their eggs in the substrate. The second group are the 'egg-hangers', those that usually spawn on plants to which the eggs then adhere.
Killifish are either of the short-lived seasonal or "annual" species or they are of the longer-lived non-annual species.
- Seasonal or "Annual" Killifish species
Most surprisingly, some species that spawn on the bottom live a very short 'seasonal' life in mud puddles or flood plains. When the mud puddles dry up so do the fish, except for the eggs they left behind buried in the mud. When the rains come again, the next generation of fish is born to repeat this short life cycle.
Because the entire life span of these fish is no more than 8 months they are considered seasonal or annual fish. In the aquarium they also have a short life span, usually only up to about 1 1/2 years.
- Non seasonal Killifish species
These are species that live where there is always water. Most will spawn on plants though there are a few species that spawn on the bottom. They produce eggs that will adhere to the plants. These fish are longer living in the wild, usually 3 to 4 years.
Many non-seasonal types of Killifish have a lifespan of 5 or more years in the aquarium
Breeding Livebearer Fish
Livebearers are generally very easy to breed. Like most other fish, the hard part is raising the fry. Generally the parents and other fish in the tank become predators to newly hatched fry but there are several solutions to this problem.
The easiest solution to predation is to provide good cover and hiding places for the fry in the form of plant cover like anacharis* and hornwort*. This will help but some will still get eaten. Another solution is to buy a breeding net, which provides a separate compartment in the aquarium for the mother before she drops the fry. After dropping the fry the mother can be removed so the fry are separated from the rest of the tank by the breeding net. Along the same lines the mother and fry can be placed in a separate aquarium so the mother can be separated from the fry when they are born. Breeding traps are also utilized which keep the mother confined with a grating that the fry can pass through.
The fry can be fed baby brine shrimp, which is usually purchased frozen, or can be hatched from brine shrimp eggs. Also pulverized flake food, which is sold as baby fish food, and hardboiled egg yolk strained through a cloth.