I have a 150 gallon 4'x2'x30" + 40 gallon sump with a 18" fire eel, 3" firemouth, upside down catfish, and 12" pleco... I'm wanting something that will add something to the tank that would be compatible. I have always wanted the clown knife or Jardini but I understand this tank is to small. What else would work and do well in this shape of tank??