This is a 75 gallon tank. I have a large oscar ,texas cichlid ,jaguar cichlid and another fish that i cant remember the name but is very territorial .These fish are considered aggressive and mixing loaches with them will end up in tragedy as i found out in the beginning. I came home to find a floater but didnt know what happened. A week later i found another floater with a big cut . So i went to the store and got a cave the loaches could retreat to and it was a temperary fix. After a while of this setup i realized the loaches were not as active and i was feeling bad about that. At this point my local fish store said they would take back the loaches, but i grew attached to these entertaining little loaches and could not give them up. So i came up with a setup that would keep them safer and more active. I made a series of tunnels that connect to different caves threw out the tank. The tunnels are clear so viewing is very good. The loaches love the tunnels, they hang out in them and sun them selfs in the morning .They use the tunnels to commute from cave to cave. Theres 5 caves and 4 tunnels that connect them together. Each cave has exits so the loaches can rome freely outside to. When in the tunnels they can swim the width of the tank in safety. Ive seen the cichlids try and bite the tunnel as the loache just sits there and laughs now. This setup has worked very good for me . It might not have the eye appeal to some people but its inexpensive and very functionable .