How much water does a fish actually need to survive? And how long can they survive on the bare minimum?


I saw a person selling goldfish in this hot summer in New Delhi, and it got me intrigued about fish and marine life, like can they see the water they are living in? If I take them out of the water and keep splashing water on them will they survive?

In: 34

Fish “breathe” by moving water across their gills, either through swimming or by sitting in a current. If that movement stops, they start to suffocate. How long they can survive depends on the fish, but goldfish can’t survive long. You would have to run water across the fish’s gills repeatedly every few seconds in order to keep it alive.


It depends. Barely any at all if it is oxygenated and cleaned somehow. Realistically, and in nature, the biggest contributor to volume requirements is waste. They urinate and defecate in said water. In a natural environment it is absorbed and used up by plants. They need a whole lot of space.

It’s less about how much water they’re in and more about how much oxygen and waste is in that water.
Assuming it’s a fish that can breath without moving, just like a person sealed in a box eventually the fish will run out of oxygen and suffocate, the amount of time depends on size of the fish and amount of water.
Eventually the fish will also pollute the water with its own waste so even if you were constantly adding air to the water the fish would eventually be poisoned.

That’s all purely on survival, it’s very cruel to keep even small fish in small containers for long periods of times, the classic Beta in a tiny bowl. Fish we think of as fish that go in little bowls goldfish and betas require significantly more water to be happy and healthy.

1 gallon of water per inch of fish

Or 3.8L per 2.5cm for metric users.

Thats what i was told is a rough rule of thumb by the guy at my local fish store