I have four bichirs and they have not attempted to escape their tank at all. From some of what I have read, they will not do so as long as they are happy. I make sure that they have lots of hiding places, the best of food and they seem very content. One of them even comes to the top now to let me pet him. I love my bichirs. I keep gravel and several different sizes of rocks in the tank. I mostly feed blood worms and beef blood cubes. I gravel vac 2x a week ( their food can be messy ) and net out the left over food daily and do a partial water change once a week ( about 10 gallons ) . I had a cool ornament that resembled a small tree that all my fish seemed to love but finally removed it as all they were doing was hiding in it and I hardly ever saw them. Instead, I put some old clear kitchen glasses and a large clear drinking pitcher in the tank and now I can watch them and they seem to find it acceeptable. Right now I temporarily have them in a 29 gallon they have just about outgrown and am getting ready to buy a bigger tank. Mine have grown very quickly since I got them.......I did have two tanks going with bichirs and my other fish but as my pump and heater both died recently on one of the tanks, I combined them until I by a bigger tank as I need to upgrade all that stuff anyway. Raising bichirs is a rewarding experience ! I get excited everytime I can tell they have grown and they all have such different personalities.