Breeding livebearers: the basics
Breeding livebearers is one of the most enjoyable aspects of keeping livebearers. And compared to other tropical fish is relatively easy. The trick is in the raising the young. They are easier because they do not hatch from fish eggs but are born alive. The only major problem is that the parents may eat the young.
The first question to ask yourself is: Do I want to breed for pedigree or not? When breeding for pedigree you have to attempt to influence color, fin shape, and body shape of future generations by carefully selecting which two fish to breed together. One of the fascinating aspects of selective breeding is that it allows you to develop new forms and colors in your livebearers.
How to select the breeding stock?
There are two basic rules to selecting the breeding stock. Rule one. Always choose healthy parents. Do not use fish with obvious defects such as curved spines and malformed fins. Do not use sick fish. Rule two. Don’t use young or old fish. Choose fish between one and two years old. Young fish produce smaller litters and are not fully grown so you will not reliably see their adult finnage, size or body shape until they become full adults.
Can young be raised in the community aquarium?
Although it is possible to raise a few young in an adult fish’s aquarium many of the young will get eaten by the adults or other fish while feeding presents grave difficulty. Feeding crumbled flake food in sufficient quantities to feed the young will lead to over feeding and rotting uneaten flake powder that will pollute and kill of your fish. Live food that is drip fed into the aquarium is a possibility but your adult fish may eat the live food before your young get to it.
These are available from aquarium suppliers but they are on the whole too small. If you buy a commercial spawning box, make sure it is at least 12 inches long and 6 inches wide. Make sure you buy the type with a separate compartment at the bottom that allows young fish to fall into to evade the mother. Better still make your own. Make one that is at least 12 inches by 8 inches big. Use narrow plastic piping from a DIY store with bendy connectors and put together a framework. Cover the frame work with some fine netting material such as that from net curtains.
Put some water sprite or crystalwort or other suitable floating plant in the spawning box to provide cover for the young fish and a bit of greenery to relax the mother fish. A week before the female is expected to give birth place her in the box. Don’t leave it too late as she might get stressed and give birth prematurely resulting in the young being still born. Once the mother has laid all her young then she should be removed. Note, she might not release all her young at the same time.
Livebearer breeding tanks
For the smaller livebearers you can use an aquarium or that is 20 liters. For larger livebearers an aquarium of a 56 liters or larger is recommended.
Equip the aquarium up with a heater, two sponge filters, some aquarium plants. Fill the aquarium with water from the main aquarium.
Place the female in the breeding tank when she looks pregnant, but make sure she is in the aquarium at least one week before she gives birth. After she gives birth returning to the main aquarium. This system is fine for most people.
A more advanced method of breeding livebearers
Setting aside a large 120litre aquarium with a large plastic netting material that dips in the water weighted down with a stone is one method professional breeders use. Clip or peg the netting around the sides of the aquarium. The netting must have gaps of about 4mm. Big enough for the fry to escape the adult fish and small enough to prevent the females swimming through or getting fins caught in the netting. Use some bushy plants to provide cover for the female to help her relax as well as cover for the fry to escape while they find their bearings.
This system allows you to just place any female and let her give birth in the same tank as other females. Once a female has given birth remove her. The only drawback is when later broods are born in the the tank alongside earlier broods. The bigger young may eat the newly born fish. When this happens you will have to use a new aquarium or remove the larger young.
How can you tell the right time to move the mother for birthing?
The gravid spot, which is a dark spot that appears in the abdomen of the mother when the fry have developed inside her abdomen. But this is only an indicator and is not reliable. The best way to tell when your female is about to drop is when her abdomen has “squared off”. This means that when you look at her from the side, her abdomen is as deep at the back of the abdomen as it is at the front of the abdomen. Before this squared off profile is reach the front of her abdomen will be deep while the back of the adbomen will be higher and less swollen.
Try to move the female before she squares off to the breeding tank. At least a week before her due date is ideal. Another way to tell the due date is to work forward from the day she was impregnated. Four weeks later she should be giving birth. If you move her any closer to the due date, you risk stressing her and she might release her brood prematurely. It also makes sense to minimise the stress of moving her by gently catching her in a large plastic container by encouraging her to swim into it and then lifting the container with her in it.
All breeders should avoid cross breeds.
To avoid cross breeding your fish including inter species breeding, you need to follow some common sense rules
- Don’t have fish in the one tank of the same genus such as Xiphophorus which includes platies, swordtails, etc or mollies with guppies of the genus Poecilia.
- Don’t have different varieties of the same species in the same tank. This is to prevent pedigree fish creating mongrel colours and finnage.
- If a batch of hybrid young are produced do not raise them, sell them or give them away.
Inbreeding is a problem of pedigree breeding over several generations
After 3 or more generations of in-breeding between closely related fish genetic problems will arise.
Signs of genetic problems are:
- Body deformities and malformed fins
- Large proportion of dead young are born
- Fish fail to reproduce
- Brood size is small even for fully mature fish
- The young fail to thrive and grow to full adult size
- Most of the fish die before becoming adults
When several of these events start to occur you need to immediately introduce new blood. You need to obtain fish of similar pedigree that are totally unrelated to your fish. Professional breeders try to avoid this problem by having two or more parallel groups of fish in development with the same pedigree. These different groups are not allowed to breed with fish of the other groups. When the gene pool deteriorates due to inbreeding then fish are cross bred between the different groups to bring some fresh blood into the group. This allows inbreeding to carry on for even longer. However, even this system will eventually lead to problems so you will need to obtain unrelated fish eventually.
Raising livebearer young
There are two main aspects to raising healthy young. The first is to maintain good clean water that is if possible slightly alkaline and slightly hard. Good filtration is a necessity. Make sure you use mature filters with a healthy colony of purifying bacteria embedded. Syphon dirt from the tank every day and top up with mature water.
The second aspect is to feed well. This is achieved by feeding little and often. Feed several times a day. When very young livebearers will take live food such as daphnia and baby brine shrimp as well as green water.
Breeding livebearers can be very easy or it can be more complicated. The more effort and skill you put into it the better the results. Good luck in breeding your fish.