Food for thought:

A lot of people like to keep catfish, knife fish, big plecos and other such nocturnal fish with their Oscars. I love catfish and have kept many - but after installing night lights on one of my tanks I was struck by how active these nocturnal fish really are.

Sleeping Oscars
+ active nocturnal fish
+ confined area
= bad nights sleep for Oscars

Since I love my Oscars and want to spoil them rotten, I do not keep any nocturnal fish with them.

Any comments?

That sounds perfectly reasonable. I've had my Oscar for four years or so. He's recently taken to spending his nights resting on the bottom, out of the way. I did have loud outbursts for a few months at night but I'm fairly certain that it had more to do with the Arowana and the Oscar bumping into each other in the darkness. My Clown Knife is very active in subdued lighting, in pitch blackness it's more likely to hide. Every fish will have a slightly different personality. I guess it all boils down to experimentation. Like I said though. That certainly sounds like a solid theory.

One of the reasons why I won't be having catfish in my new tank. I've had a couple of syndontis catfish for the past few years and they do nothing but hide all day. So, from my experience with catfish, I actually don't see any point in having fish that are only active at night.

I have often wondered how much sleep fish get with nocturnal fish present. Very good point to bring up though, I'm sure that this discussion could go on for a long time

Question - do oscars, or any fish for that matter, sleep like we do? or do they rest? or something else. I remember hearing about some animal that lives in water (cant remember what) that cant sleep and breath so it sleeps one half of its brain at a time.


Also in the wild some of these nocturnal fish would be predators so i would expect oscars to be 'keeping an eye out for them' so maybe they sleep light

Most fish would find shelter when they sleep. They wouldn't just sit in the middle of the river and go to sleep, that would be asking for trouble. Even though the fish are normally quite safe in your tank, I think it's a good idea to include hiding places. Most of them are bred in captivity but they will still have the instinct to hide away. Couldn't really tell you how well they sleep, I know they do sleep for quite a while. Never heard them snoring though

Some people don't think fish sleep because they don't close our eyes, crazy, but true