One mistake I have made in using an aquarium was to make it a complete setup. I put in live plants, driftwood, cichlid sand, etc. The tank looks great but it is going to be impossible to to net them with all the cover. I will probably end up removing most of the structure when it comes time to sell some so I can seperate them from the Goldfish and catfish. My thinking with the plants was for extra biological filtration of the extrerme nutriant load they cause, but I have another 55 gallon tank with 125 CNBG that has only the glass bottom and a Bio-Wheel/ mechanical filter. I change 75% of the water daily and my ammonia levels stay near zero. Doing that on the 135 gallon with the Tilapia and catfifh is a LOT harder.
