1 inch per gallon

[severum mama]

Okay. Thanks for all of the input. Recently my friend went to Petsmart to get some new fish since she had no more fish, and she wanted to buy 4 neon tetras, 2 buenos aires tetras and two ghost shrimp for her ten gallon and they wouldnt let her because they can't guarantee her fish because of one inch per gallon. Were they right? Would it be too much? She ended up just getting the neons and ghost shrimp.

They were right to not sell Buenos Aires tetras for a 10 gallon tank because they are not suitable for a 10 gallon, but they refused the sale for the wrong reasons. Going by the inch per gallon "guideline", you could keep a few Buenos Aires tetras in a 10 gallon, but they would be a terrible choice for the tank as they grow too large and are much too active. IMO adults will need a minimum of a 3' tank. The inch per gallon "guideline" is utter nonsense and will more often than not steer a hobby newcomer in the wrong direction.

 

[T1KARMANN]

If the 1" does work that would mean you can keep 1 x 10" fish in a 10 gal right

 

[Delapool]

Is anyone willing to run it on their tank? We have real life fully stocked tanks to test the guideline it seems to me. I suggest keeping it a simple post of tank volume, fish inches (or even just the calculated %), type of fish and any observation (last two are just information really). Or as detailed as may be wished.

 

[pip walters]

It's a terrible rule because you could say that 10 guppies could fit in a 10 gallon which is a less extreme example than the 10 in Oscar idea but is still a really bad stock.

10 guppies in a well filtered 10 gallon is fine - I know of guppy breeders that use smaller tanks for their breeding fish!

 

[pip walters]

I tried pacing that out, and now I'm just jealous

It would be useful to know why the fish shop uses the rule.

Because this was the rule set by 'experts' in the past. These 'experts generally turn out to be advanced hobbyists who have little if any scientific background.

 

[pip walters]

What we have to remember also, I think, is that fish grow in three dimensions, not just length. A buenos aires tetra of 2 inches may weigh twice or three times that of a 1" fish and produce 2 or three times the waste, thus needing a larger turnover of water to remove the waste efficiently.

I know I keep using carp as an analogy, but I know carp! A 2-3" carp weighs on average 5g. A 3-4" carp weighs on average 15g - that is triple the weight for a one inch gain in length.

It stands to reason then that the 1" per gallon rule may mean that for each inch of growth, the fish need three times the room? Not necessarily, they may just need three times the filtration!

 

[Delapool]

Good point, many thanks for the information.

 

[T1KARMANN]

What we have to remember also, I think, is that fish grow in three dimensions, not just length. A buenos aires tetra of 2 inches may weigh twice or three times that of a 1" fish and produce 2 or three times the waste, thus needing a larger turnover of water to remove the waste efficiently. I know I keep using carp as an analogy, but I know carp! A 2-3" carp weighs on average 5g. A 3-4" carp weighs on average 15g - that is triple the weight for a one inch gain in length. It stands to reason then that the 1" per gallon rule may mean that for each inch of growth, the fish need three times the room? Not necessarily, they may just need three times the filtration!

Some kio keepers base the stocking levels on the total weight of the fish which I feel is more accurate on larger fish

It's working out at what size tank you move from the 1" per gal rule to the mass of a fish