Do fish get thirsty?

[KatiePrice]

Do fish get thirsty.... my crazy brother-in-law wants to know!

[wildwood]

No. Fish live in a wet environment where all their food contains a high amount of moisture. Even the dry flakes we feed the gold/tropical fish is soaked by the time the fish get to it. They don't perspire either.

[marabout]

what a fantastic question! had me thinking!...and an informative answer...one for the tea table crowd tomorrow night!

[hammerman]

I'm going to beg to differ on that. I'll have a proper look some time but iirc, freshwater and saltwater fish are different in the way water enters and leaves the body through osmosis.

One of the types....possibly saltwater fish, have to drink constantly as the water loss through the body walls is constant due to osmosis where as the other type of fish has to constantly urinate as the intake of water through the body is constant. As i say, the old memory isn't as good as it used to be so i'll try to find out for you.

However....as mentioned, fish don't get thirsty as in...."oh i could murder a pint" !!!!!!!!!!!!!!

[Thunderbird+]

Not a crazy question as it may first seem, tell your brother-in-law.
For most fish getting a drink of water would be no problem but if that fish happens to be an amphibian-like fish such as a Mudskipper which spends 3/4 of it's time out of the water then Yes! it will get thirsty from time to time and will feel the need to go back into the water to store some water in it's gills, this is how it manages to survive for so long out of water!
When on land it uses it's modified pectoral fins to walk along on the mud and tree roots.