This is the problem with common names.Rainbow cichlids are African so keep that in mind when considering water parameters


Yes, they do max out at around 4"-5", and if it were me, I wouldn't keep them with oscars.I thought the person who posted that was talking about Australian Rainbows myself. Aren't Rainbow Cichlids pretty shy and stay about 4 inches? Probably not a good idea with a full grown Oscar.