a similar situation happened to me once where i saw a giant gourami (8~9inch) and an oscar(7 inch) cramped into a 40 gallon tank at a hotel...the gravel was all dirty and upon close inspection i noticed that the only filteration available was a
powerhead filter that too with a rating of only 600L/h....
i did talk to the manager and after a long debate convinced him of taking atleast one of em out and giving them off to a
LFS...
the next time i went there i could see only the oscar...
better if not entirely perfect i assume!