When you come into the shop on Friday ask to see me as I will be anywhere except on the fish section.
When talking about ratio's of fish, it can be a bit of trial and error. At home a lot of my tanks were heavily laden with males, as a lot of people would go for female heavy groups. I soon found out that a lot of males to even one female worked really well for breeding. Sometimes there was as many as 6 males to 1 female. It was a good breeding strategy. What actually happened was, the alpha male was in full colour and the others progressively were a duller colour as they went down the ranks. No other male ever got near the female as the alpha was there to protect her, non coloured males are not interested in breeding. Because the alpha male was in breeding colour and fighting colour it seems as if he was more attractive to the female and she would respond to his advances, if the breeding was unsuccessful I would take the alpha out and immediately others would be trying to take his spot and I would guarantee the female would be holding within a day or two.
Too many times I have tried trio's of 1 male and 2 females, sometimes this can work but I have seen many times when the odd female his harried by the breeding pair, sometimes to death. I have also noticed that when 2 females are present the male seems not to try to hard, if you know what I mean. This leads to the females being not being interested in the male and the male then is constantly chasing the female and she does not respond. Mind you if you put a mirror in when this happens, the male starts to attack the mirror and 9 times out of 10 the female will then respond.
Pairs are good to keep, but I would never have just 2 males as 1 will virtually always make the others life a misery which can lead to disease. 3 males are a much better option than 2 as any aggression is shared. On the whole It really doesn't matter on the amount of females as it will mainly be the alpha male that breeds, but again I would avoid having 2. 1 or 3 is my general rule whether male or female.
If it is a fairly rare fish I would go for groups as these sort of fish don't come about often and you don't get the F1's about. If you want them to breed go for male heavy groups. Otherwise I would go for pairs, unless of course its a fish that you really like then have a group anyway
