I have a 70 gallon tank with one rope fish and one palmas or marbled bichir. I had two ropes but one got that weird thing where it swims around upside down and then dies a day or two later. I change about a third of the water once or twice a week. I was wondering if there is room in the tank for two more ropes and if anyone has an explanation as to why the other rope fish died? It had no discoloration or white dots or anything. Is it even possible that this happens from head trauma from trying to jump out of the tank or something?