1cm of fish per liter of tropical water?

[Ags1]

I recently encountered this rule online - it seems very high compared to 1 inch per 2 gallons. Does anyone follow this rule?

The rule also changes to 0.5cm per liter for unheated water. Why would that be? The cold water will hold more oxygen and the aquatic creatures will have lower metabolism, so not sure why carrying capacity would be half.

 

[Aiken Drum]

The normally quoted rule is 1 inch per gallon. So, a more accurate conversion would be 0.7mm per litre.

Cold water fish tend to be messier, so they need more water and better filtration than a tropical fish.

 

[Ags1]

"Cold water fish tend to be messier, so they need more water and better filtration than a tropical fish."

Is that a general rule, or just goldfish and barbs?

 

[Aiken Drum]

Ive just seen it as a general rule and reasoning, although goldfish are always the cited cold-water fish. Certainly true for goldfish, but as you say, if you put a goldfish in a heated aquarium they become even messier. A temperate barb though, you would be good at 1 inch/gallon.

I dont really prescribe to the rule though beyond a rule of thumb, there are so many factors it doesn't account for.

"Cold water fish tend to be messier, so they need more water and better filtration than a tropical fish."

Is that a general rule, or just goldfish and barbs?