Oh, Cichlids would be nice. Yellow Labs and/or Acei, I have a mixture of those two and an albino BN in my 55g. The cichlids dig when mating but if you put egg crate below the gravel and keep replanting the plants they eventually take hold. Cichlids like to be heavily stocked so you can put more in there (with the increased filtration), they're bright, colourful and fun to watch! I swear mine recognize my husband and I, they always come out when we're in front of the tank but if a "stranger" looks in they hide.