[naiad]

That is one fish I would like to freedive with - a 20 stone carp!

When I moved my fish into their new outdoor tank, I had to scrub the algae off the old one. The green and brown algae are surprisingly abrasive, like very fine sandpaper, and my fingernails were soon worn short by it. The fish nibble away at it all day, so I guess their lips must be extremely tough to avoid damage. Maybe the skin is constantly replaced as it wears out. Carp do have very tough mouths.

Another strange carp is found in lakes in Portugal. It is exactly the same as a normal Common carp, except that it has huge and wrinkled lips. A high percentage of carp in these lakes have this feature, and they seem otherwise healthy. One theory is that they use their extra-tough lips to tackle crayfish.