Hi just wondering how many fish I can keep in my tank currently running ehiem pro 3 filter with bio home ultimate in and also polishing cloth etc and also running a fluval u4 atm as that was with the fish in my tank before so will be staying in till ehiem is established currently have two featherfin catfish one around 7" and one about 4" and two cichlids would like more fish in there would I be best staying with cichlids and the catfish or could I mix it up abit?