I dont plan on keeping a large group.. i plan on keeping a pair. that would be the goal.. to have the two fish together in one tank, that is small enough so that they would be forced to see eachother all the time, with little to no aggression. Far fetched, maybe but not impossible.. As you probably know Brandtii like the piraya come from the Rio Sao francisco river and its tributaries.. In research i was looking at the different varients of rhombeus produced in different locales, and the physical differences can be very extreme.. Changing color, body shape, head structure, maturity age and other things aswell depending on where the fish was collected. Upon inspecting pictures of serrasalmus brandtii from the internet you will notice two distinct color forms, both gold and silver. Seeing that this fish is only collected from the confined space of that single river i find it hard to believe that there would be changes in the fish do to the environment so I am looking in to the possibility of sexual dimorphism in this specie.. Im not saying that my ideas are correct im just saying its a possibility and i havent heard of anyone trying this yet.. so i proceed to step outside the box and try something new.. Same idea (cohabitating them) different technique.. Obviously it is not impssible to cohab serras, i have seen it done before but i believe it only works when its beneficial to the fish.. having such a large group IMO triggers the fish to see the other indivduals of the shoal as a threat, and they show very high amounts of aggression.. I believe that when it comes down to it, its really up to the fish, not us whether or not they will let it happen.. Correct pairing of the fish will also play a major role. i will let the fish see smell eachother through a divider for a lengthy period of time before i even let them swim together for breif supervised minimal amounts of time.. I tried this with my brandtii and an irritans a while back.. my brandtii is a killer, in all seriousness, but didnt show any aggression to this irritans through the divider, only when the irritans started to attack the divider did the brandtii retaliate.. he was more interested in "checking out" the irritans. This might be due to the fact that an irritans is silver, like some brandtii. Thsi is where i get the idea that the color difference is marking sexual difference..
I am in no way an expert i just took the time out to locate as much information as possible.. i am looking into another brandtii at this time and will hopefully have it swimming in one of my tanks in the next couple of weeks.
and you probably find out of your fish is male or female.
