Eigenmanni piranha?

[Ad@m]

every piranha will fight... serra's will fight more than pygo's.
So for your 55 gal., i say try and track down an S. Irritan or get a brazilian eigenmanni. both look great and i have heard of nothing but good things about there aggression. and they can live in a 55 for life.
you can find them at http://www.aquascapeonline.com/

 

[---XR---]

If you got a 55 I my self would go manuli

i wouldn't, manny's have hit 20" in the wild and it bound to happen in captivity one of these days.

 

[Plum]

Yes - 55g is too small for a Manny for life. Might be fine for the first bit, but you will need to upgrade.

Shoaling serras..... not likely. Geryi can be shoaled - and I am having luck with the three I have. But I do have another one that has to be kept solo. He is a devil, will kill anything.

I have heard that some people with mac's that are able to shoaled, but for one, it does not seem to be long term - and it does require much attention.

As for the other species - if you are not going to follow the failed attempts of others - at least have a huge tank - think 180G plus.

Plum