Again - the hardest thing is to prevent leaks, spills, on electronics. What type of fish tank set up= salt vs fresh vs brackish. Heat is a killer for fish and electronics - so must have a great cooler system. I think it must be a fresh water setup as the salt stuff is too sensitive. How big? The gallons of water to fish ratio must be high = not many fish and for them to be able to swim through the tubes ( very neat) they must be small. Unfortunately, small fresh water fish don't live that long- so you have to be able to somehow reach in and remove debris( waste, uneaten food, etc) and the eventual dead fish. You could do this or prevent this by having enough current to cause it to collect in a certain place and then use a type of water vacuum.