Most aggressive fish for a 55 gallon.

[guppy]

A whole swarm of pike top minnows (belonesox belizanus), 3-4 females and 8 males in a planted 55g would be sweet. The pic is by Johnny Jensen. The picture is just a tiny bit bigger than life size for a larger male and a little small for a female.

 

[DiXoN]

A whole swarm of pike top minnows (belonesox belizanus), 3-4 females and 8 males in a planted 55g would be sweet. The pic is by Johnny Jensen. The picture is just a tiny bit bigger than life size for a larger male and a little small for a female.

those are nuts little fish very quick and a sight to watch when feeding

 

[HarpoGarza]

I'd go with a Red Devil. I can't wait to add one to my 125.

 

[Skoomakilla]

i agree a red devil or you could try a red terror(feste cichlid) if you can get ur hands on one srry about the spelling

 

[MrfisH]

I would go with a Green Terror. They have the whole package, beauty, aggression, and can live in a 55 for life.

Let me know how that RD works in your 125 Harpo. My Devil destroyed my oscar and was at a 4" disadvantage.

 

[African Dick]

Really? I googled exodon tetras and on like 3 sites they said that they're suppoed to get to 7". How long have you had them? Maybe they just grow slowly. How big is the tank and what kind of stuff do you feed them?

I have had them 7-8 months and they have barely grew. I feed them 3 times a day. They are in a 55 gallon.