What Ever Happened to a Fish Only Having a Five Second Memory

[Colin_T]

Aren't fishes colour blind ?

No.

Fish have very good colour vision and in most cases they see more colours than people. They can see UV light as well as most other colours. It's one of the reasons fish are colourful and some fish show different colours under UV light.

 

[GaryE]

Yeah, I think a lot of fish could pity us for being colour blind.

The old line there's no such thing as a fish comes into play here. The things we call fish are from several different starting points, and each pathway in their evolution gives them different abilities. We throw a bunch of different things together for convenience under one name, but how their vision works varies a lot, even across the species we keep in tanks.
I'm being a bit of a nerd here, but it fascinates me. For years, on Forums, people only talked about the Cycle. Now, I see discussions about the water needs of the fish species we want to keep. Suddenly, there is more awareness of soft and hard water, and how fish are adapted. It's a giant leap within the hobby, to an area neglected for a couple of decades. Lighting, water depth, minerals in the water (or not), diet, and most importantly, diversity. Once we get excited enough about those ideas to want to dig into them a bit, this hobby gets really interesting.

I make youtube videos about fish in aquariums, but the videos I like to watch are of fish in the wild. If you look at sites like below water, or Ivan Mikolji, it's fantastic stuff. The algorithms on line don't make them easy to stumble across because, well, that's the commercial internet now for you.