ITS 120 GALLONS, I CHANGE HALF THE WATER EVERY 2 WEEKS, VACUME ONCE A MONTH, 1 BIG OSCAR, I PIKE, I GREEN TERROR, 1 JACK DEMPSY, SPINEY CAT FISH. IT SMELLS LIKE FISHY MOLD, I THOUGHT THE WOOD TOP WAS ABSORBING MOLD SO I REMOVED IT AND IT STILL SMELLS SOME DAYS ITS WORSE THAN OTHER DAYS