The whole success of fish tank breeding of platies depends on the quality of the breeding ornamental fish and its blood line.
Finding quality ornamental breeding platies
Here there is some trouble for you in purchases of ornamental platies from the pet stores. Most of the pairs kept in tanks at the pet stores found to be really not matched pairs.
The female and males may be coming from unrelated strains of fish. There are too many hybrids among the xiphophorus species flooding the ornamental trade.
If you are starting with a poor strain it will be beating around the bush for you and it may take a long time till you perfect a breeding line.
Join the local club of hobbyists. You can learn a lot as there are many senior hobbyists willing to share their experiences. You may also come across persons willing to sell high quality ornamental parents.
Fish breeder sellers of repute or hobbyists with good standing will oblige and you can hope to get true lines from them. Request them to give you virgin females and young mature males.
Buy one or two sets of trios (one male and two females) of the same ornamental strains; if same strains are not available try to get at least closely related strains.
See to it that the male has the best traits you wish to improve upon. The female must be matching the color characteristics and fin characteristics of the male.
A stronger and bigger caudal peduncle region usually is a sign of a healthy fish and the possibility of more babies. Older males are found to have trouble mating and there are chances of greater deformities among the progeny of older parents.
If ornamental females are already pregnant then you cannot be 100% sure that they carry the babies of the males you have.
You may have to wait for 2 – 3 broods for getting the babies of the selected male. You cannot hope for quantum jump in breeding new lines of ornamental platies.
You have to be persistent and focused in breeding a true fish line. You have to decide which color or fin shape you want to work on, limiting your choice to one trait of the ornamental platies; breeding this way you can develop a true line.
Breeding more than one trait at the same time will lead to mediocre fish not excelling in neither of the characteristics. Many possible strains of ornamental fish are lost due to indecisiveness in breeding programme which instead of staying focused leads to bouncing around.
If you want to work on more than one trait then conduct separate experiments with separate breeding platies and never mix them up.