The Fish Vet's Blog

Do fish drink? Where did the phrase come from? Is it because they look like they’re continually gulping that people think they’re drinking all the time?

The constant movements of their mouth is actually so that they can draw water past their gills in order to breathe.

So, do they drink? Well… fresh water fishes don’t really drink all that much. Their skin and gills are somewhat “leaky” and they actually draw water into their body passively. The excess water is excreted through their kidneys as dilute urine. The opposite is true for marine (salt water) fishes. Body fluids are lost through their “leaky” skin and gills and they counteract this by drinking a lot of water and producing little urine.
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A tank.

Dr Richmond Loh
BSc BVMS MPhil MACVSc
The Fish Vet, Perth, WA.
+61 (0)421 822 383
Veterinary medicine for fish & other aquatic creatures.
http://www.thefishvet.com.au

Generally speaking, the larger the fish, the longer they’ll live (interestingly, the reverse is true for pet dogs). Most fishes in retail outlets are sold either as juveniles or young adults. Fighting fish for example are already >5 months old when sold at aquarium stores at >5cm in size. They have a lifespan of up to 5 years, but more commonly, 3 years.  Goldfish can live for 20-25 years, but 10 years is more common. Similarly, oscars live for about 10 years. Kois (Japanese carp) can live in excess of 50 years and even up to 100 years! It’s a fish that you’ll have to pass on to your children. On the other hand, some killifishes are annuals and can live for 1-2 years in captivity.

Sadly, the average lifespan of a fish kept without adequate filtration and filter cycling may be as short as 4 weeks. The reason for this can be found in an article from my website – http://thefishvet.com.au/pdf/Ncycle_byRL.pdf

Little Nancy was in the garden filling in a hole when her neighbor peered over the fence. Interested in what the youngster was doing, he asked, “What are you up to there, Nancy?”

“My goldfish died,” replied little Nancy tearfully with- out looking up, “and I’ve just buried him.”

The neighbor laughed and said condescendingly, “That’s a really big hole for a goldfish, isn’t it?”

Little Nancy patted down the last heap of earth then replied, “That’s because he’s inside your cat.”

It makes sense when you appreciate that 70% of the earth is covered by ocean. The ocean is also a large carbon sink. Thus it is very important that we look after it.