You might want to keep an eye on aggression. I was worried about purchasing some after reading up on their reputation for being really nasty little buggers, very aggressive amongst themselves and conspecifics. I asked the dealer who I baught them from if they deserved the bad rap and he didn't hesitate to answer yes.
Out of 10 I purchased I have 4 remaining, 1 female and 3 males, in a 4' tank. I can't take out the extra males or the dominant males will kill the only female so I'll wait till I can purchase some definate females.
I suggest you purchase as many as you can at once so that their aggression is evenly distributed. Try to narrow the group down to one male and as many females you can make out in a 4' tank minimum. This is a great place to start for a potential breeding colony.
Both sexes are vividly coloured which can make sexing very difficult though the males often have darker black/dark blue and brighter almost white bars. Females sometimes lack the solid dark colouration under the chin or it is very muted compared to the male's colour. The male's fins are also longer and more pointed. The ventral fins are long and can reach the anal fin, the dorsal edge long and pointed. Your demasoni will start showing breeding behaviour as early as 1 1/2" and begin breeding at 2 - 2 1/2". They might breed sooner or later depending on the conditions they're kept in and the condition on the fish themselves.
These are great fish with loads of attitude for such a small package! Perfect for anyone who likes fish that don't take no crap from nobody.
It appears that I have 2 males and 1 female...
