Looking for a SMALL nocturnal oddball fish, then i recommend this fish:
(not my photo, taken form the internet!)
Its the midnight catfish, we have had one in our new 47gallon set up for a month now and when we turn off the light and turn on the moonlight leds out he comes looking for food!! He swims midwater is a very busy little guy and loves frozen foods especially cockle! He'll only grow to 4-5 inches long so is perfect for the smaller set up!! We are going to ask our LFS to get some more for us soon as they seen to be a great addition!!

(not my photo, taken form the internet!)
Its the midnight catfish, we have had one in our new 47gallon set up for a month now and when we turn off the light and turn on the moonlight leds out he comes looking for food!! He swims midwater is a very busy little guy and loves frozen foods especially cockle! He'll only grow to 4-5 inches long so is perfect for the smaller set up!! We are going to ask our LFS to get some more for us soon as they seen to be a great addition!!