I would have to agree with him - That turtle alone.... serious bio-mass waste, let alone the fish... However, you always want to provide as much space as you can for your fish / pets... I wouldn't say there's not enough room in this tank for these guys at the moment, however the filtration is not sufficient and you lack some good flow... That's my two cents but I can never understand why people keep feeders as pets?
Well. The goldfish i have were intended as food. But. Survival of the fittest i guess. Filtration information: filter is a Fluval U4. Current is active throughout the tank. Suggestions on improvements?
Now if you install a state-of-the art toilet in said elevator and a state-of the art air purification system and reduce the amount of people, then maybe the people could be somewhat happy in said elevator for an extended period of time.
Oops. Unintentionally lied... its a u3. Further research proved my memory wrong. Sry. What then do u suggest? Can't get rid of anyone and can't get a bigger tank. My options are limited.
One more thing, because I think its really important to point out here, fish keeping and fish management is as much about waste management as it is about anything else. A closed system is, exactly that. And I think this point is more important than tank size and number of inhabitants.