My tank is 150G with 10 Clowns and 3 Yo-yos. Lighting is just standard. I'm guessing the biggest loach is about 6-7 inches long. Four are about 6 inches, two around 4-5 inches, and the smallest three about 4 inches. The plan is to get a new tank in the future so big I can dive in with these guys! (half joking) It would be great to get a DSLR camera too!