Fish Breeder

What is involved in Breeding Fish?

Depending on your purpose, general interests, and the availability of suitable resources, you may choose to raise one or more species in freshwater, salt water, brackish water or include them in an outdoor pond. Whichever way, and whatever species you choose to breed, it is highly necessary to find out the specific living requirements and lifestyle habits each species has.

Freshwater Breeding

Breeding fish in freshwater aquariums is probably the most common ones nowadays. Community tanks are the most popular ones, but single species breeding is also well-liked. Freshwater breeding may be done in aquarium tanks as well as in garden ponds. Some commonly bred freshwater species may be: Goldfish, Guppies, Angelfish, Mollies, Catfish, Killifish and Danios, among others.

Saltwater Breeding

Saltwater breeding is ended for more experienced aquarists due to a higher level of maintenance and significantly higher costs in terms of species (exotic or reef species are less common in fish shops, which makes them more expensive to buy) and equipment care (corrosion may lead to buy new equipment, or more expensive equipment to avoid it). Some common species to breed in Marine or reef aquariums can be: Coral reef fish, shrimps, crabs, molluscs, corals, echinoderms, algae, sponges, worms and live rock, among many other species of interest.

Brackish Water Breeding

Brackish water breeding resembles that of mangroves and estuaries, which means, the salinity levels are a mixture between saltwater and freshwater.  Some species bred in mix water tanks may be: Gobies, Pufferfish, Monos and Scats, among others.

Alternative Pond Breeding

Certain aquarium fish species such as Goldfish may be more easily bred outdoors in ponds and the eggs that have hatched or young fry should preferably be raised in tanks.  Breeding cold water pond fish is relatively easy provided the correct conditions are presented.  Breeding is generally triggered by an increase in water temperature and longer day lengths, which is a naturally occurring phenomenon in spring and summer.  

For outdoor ponds, it is advisable to have a submersible heater that can be used to bring water temperature gradually up to 20-23oC, which will promote spawning.  A suitable surface needs to be provided for the fish to lay their eggs onto; this allows the eggs to be removed after spawning if they are to be hatched in a separate pond or tank.  String mops, plant material and other suitable surfaces can be used for egg deposits.  Where fry are to be raised in the same pond as adults, screening will be required to keep the adults separate from the eggs and young fry and prevent them from being eaten by their parents.  If eggs are to be removed to a separate hatching area, the water temperature needs to be kept at 20-23oC with eggs hatching in 2 weeks.  The young fish will feed on naturally occurring algae and other foods in the pond, however those raised in tanks will need supplementary feeding.

Tank Set-up and General Requirements

Setting up a tank for breeding purposes will allow the fish to spawn freely without feeling threatened by the rest of the fish, as well as to have their own space, avoiding territorial aggressiveness. A separate aquarium is optional when fish are just about to spawn to avoid the fry from being eaten by the parents or by other adult fish present in the tank.

The size of the tank for breeding purposes should be a reasonable size in order to achieve success. For large fish, a 40-80 litre tank will do, as for smaller fish, a tank with 7-20 litres of water should be enough. After breeding, this tank will be useful to raise the fry after hatching (some species guard their young after they are born, so they should be kept inside until they have stopped breeding).

Fill up the tank to a half with water from the main tank (where the adults were taken away from) and top it up with clean pre- treated and adjusted water. Although every species has specific living requirements, no decorations are necessary for a rearing tank for the majority types of fish. A thin layer of gravel should be enough to supply the fish a nice enough environment along with allowing easier cleaning processes. For most egg-laying fish, the presence of plants might be useful.

A good filtering system is essential when breeding fish in an artificial environment. Protein foam filters are a good option as they supply an efficient and gentle filtration. Make sure the air pump is the right one or adjusted to the size of the breeding tank. Another good alternative is to use sponge filters due to their multiple functionality, serving as a biological and mechanical filter, as well as providing gentle turbulence required when eggs are laid or fry’s hatch.

Regular water changes are also necessary to maintain a healthy living environment for the fish being bred, as well as for the survival of fish eggs and fry. Fish eggs alone in a tank do not require frequent water changes as they do not produce waste products as such. Small fish fry, on the other hand, require regular water changing, but, at this stage, this may be done by simply siphoning the dirty water out and any residual wastes into a clean bucket free from chemicals or detergent just in case some of the fry get sucked out.

Temperature requirements for each species are important to keep in mind. An aquarium heater and a thermometer should suit the needs to maintain a steady temperature when required, as well as raising or decreasing the heat to encourage spawning processes.

A cover or hood for the rearing tank is advisable in order to keep the breeders inside as they might be nervous at this stage and attempt to jump.

Early Stages - Selecting and Conditioning the Pair

Some species, as explained above, will only breed by certain stimulus or environmental changes just as others will breed without any incitement. Guppies and Swordtails, for example, will easily breed on their own with little or no intervention, while other species will need to show a noticeable courting behaviour for the aquarist to know they are ready to breed. 

For those that need stimulation it is good to place a glass separator between them so they can see each other but not be able to mate. This way, the pair becomes more likely to mate when the separator is removed. It is important, however, to research about the life cycle and spawning characteristics of the species to breed in order to achieve success in the rearing scenario.
First thing to begin with is to select the right pair.  Start by distinguishing the two sexes apart and choose the healthiest looking ones. Some characteristics that might help distinguish the healthiest looking fish by appearance are those that have the following qualities:
  • The brightest colours 
  • Good markings
  • Good finage
  • Vital movements
  • Good appetite
  • Preferably young age but mature enough to breed (younger ones are still in their prime reproductive cycle)
  •  Compatible within each other (you may often notice compatibility only after months of watching their behaviour in the aquarium)

Note: If cross-breeding strains are desired, it’s important to keep in mind that the hybrid might not come out with a nice physical appearance, and it may also be sterile.

Once the parents are selected they will need to have the space and comfort to spawn. To achieve this, make sure the environment in the tank feels like a home to them by replicating the physical appearance (i.e. ornaments, plants) and simulating the water conditions (i.e. parameters such as temperature, light, etc) to their natural habitat. Also, make sure to find out the specific needs and characteristics the species require during their spawning events.

Triggering Breeding

Some fish species will breed all year round in a suitable aquarium environment; however others are naturally seasonal breeders and often require a trigger to stimulate spawning.  Often this requires simulations of the rainy season with reducing the water level, then increasing it again with frequent water changes, or changes in food supply (provision of live food) or an increase or decrease in temperature, some fish may be triggered by increasing day length or light intensity.  Knowing which triggers are required for the fish species to be bred is vital and these conditions are best provided in a separate breeding tank.


Fish breeders supply fish both for use in aquaria (e.g. as pets), and also for fish farming and aquaponics.