Do fish drink water?

You’ve heard of the saying, “To drink like a fish!” But do they drink? This is a question posted on my Facebook Fanpage today.

I’m going to give you a ‘yes’ and a ‘no’ answer. Let me explain.

Marine fish do drink large amounts of water to maintain hydration. They produce small amounts of minimally concentrated urine. Much of the excess salts are removed instead, through their gills.

Fish that live in freshwater don’t exactly drink water, but they absorb it from their environment through their skin and gills; in a process called osmosis. They then have to expend energy to get rid of the excess water by producing lots of dilute urine.

This is why when freshwater fish get sick, they start to bloat and present with dropsy (see previous post – This is the reason for altering the salinity of the fish’s environment when they get sick.

Yours sincerely,

Dr Richmond Loh
DipProjMgt, BSc, BVMS, MPhil (Pathology) Murdoch, MANZCVS (Aquatics& Pathobiology), CertAqV, NATA Signatory.
THE FISH VET, Perth, Western Australia.
Veterinary Medicine for fish.
E: thefishvet
P: +61 (0)421 822 383


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