Practical Fish Keeping Magazine

[Edge]

Hi, I read an online article on www.practicalfishkeeping.co.uk about stocking levels. They recommend the usual inch per gallon initially, but then say after 6 months the level can rise to a maximum of 2 inces per gallon. Before you all hire hitmen to save my fish from overcrowding, I'll point out that I'm not planning to use the 2" per gallon ratio just yet. I just wondered if anyone had heard about this before, and if anyone had tried it with or without success.

 

[Tech-Frog]

2" per gallon is for more experienced fishkeepers who can handle when it goes wrong.

 

[OohFeeshy]

I wouldn't really take their advice, some of the writers don't give out particularly great advice, particularly on compatability, stocking etc.

 

[Miss Wiggle]

i think you can stretch the inch per gallon rule if your a bit more experienced and it suits the fish, the tank is clean and healthy etc etc etc, but I think doubling it is a bit off

 

[Tokis-Phoenix]

Hi, I read an online article on www.practicalfishkeeping.co.uk about stocking levels. They recommend the usual inch per gallon initially, but then say after 6 months the level can rise to a maximum of 2 inces per gallon. Before you all hire hitmen to save my fish from overcrowding, I'll point out that I'm not planning to use the 2" per gallon ratio just yet. I just wondered if anyone had heard about this before, and if anyone had tried it with or without success.

Do you have the link to the article? Personally i think its poor advice they are giving, as OohFeeshy said some of their writers aern't very good, despite the magazine being good on the whole depending on what you read it for.

 

[dwarfgourami]

Some of their writers are absolutely wonderful (not least our own Neale!) and it is a magazine I wouldn't be without, but IMO they don't often get through a whole issue without somebody handing out dodgy advice somewhere (this month's issue was the suggestion to get platies in pairs). These things do slip through.

As for the 2 inch/gallon, I'd say it's not obviously dodgy advice like the above, but it's something you should approach with a great deal of caution: are you experienced enough? is the tank mature enough? is your filter up to it? do you know enough about fish to be sure these particular fish will have enough room/not produce too much waste? have you got enough leeway in case of a sudden filter crash? etc etc etc. Personally, I like to feel that I have a bit of a margin, and I wouldn't do it. I prefer my tank to be a jungle rather than a group photo. And I would particularly not try it with a tank under 20 gallons- sudden water disasters are much more likely and much more disastrous in a small tank.

 

[Edge]

Here is the link Stocking Densities. To be fair the article does go on the explain in more detail, it just struck me as an odd recommendation when compared to the advice I've read everywhere else. There does seem to be a few different opions, I know a few people who have kept fish for a very long time, and they work out their stocking levels on a surface area basis and seem to have very few problems. In response to your advice though, I'm a new fish keeper and only have a 16 gallon tank, so I don't have any intention of having 32" of fish - that seems way over to me. We're nearing the end of a fishless cycle with our tank so as I can fully stock the tank straight away I'm just wrestling with ideas of what/how many fish to go for.

 

[andywg]

If you have the filtration, and the desire to do water changes then 2" per gallon is absolutely fine.

I know my 6x2x2 must be stocked close to that, and the same for my smaller tanks all running off the 2 foot trickle tower.

 

[basia]

Depends on the fish to some extent. My main tank has always been overstocked if I went by the inch per gallon rule but a lot of my fish a small tetras and it has an external filter plus the Jewel internal filter and my manic tank maintenance so I have never had any problems - so far...

 

[Kombat]

The inch/gallon rule is based on US gallons. That article is using imperial gallons. In it's example they use a tank that is 28 US gallons, 23 imperial gallons. Their final calculation is 42" of fish, which is not even close to 2" per US gallon.

Karl

 

[aberdeen aquarist]

The inch/gallon rule is based on US gallons. That article is using imperial gallons. In it's example they use a tank that is 28 US gallons, 23 imperial gallons. Their final calculation is 42" of fish, which is not even close to 2" per US gallon.

Karl

No its not based on US gallons. The calculation is based on UK gallons, minus 10% for displacement caused by substrate and decorations. 10% of 23 is 2ish, therefore 21x2=42.

 

[CFC]

Sorry but the inch per gallon guideline is based on US gallons and always has been, UK gallons have not been widely used for many years now with litres taking their place in UK/European thinking. I had never heard of the 1" per gallon rule until i started using the internet and found it mainly advised on US based sites.

There is no hard and fast rules for stocking, im sure no one would be really shocked to see a 20 gallon tank with 30 neon tetras in it but if the same tank had two 10 inch Cichlids in it the tank would be grossly over stocked. It all comes down to common sense and what looks and more importantly feels right, the 1" per gallon rule stops newbies from making mistakes but once a little knowledge has been attained there is nothing wrong with bending the rules providing the fish remain healthy and stress free.

 

[PaulEbs]

stock till you drop

 

[aberdeen aquarist]

Sorry but the inch per gallon guideline is based on US gallons and always has been, UK gallons have not been widely used for many years now with litres taking their place in UK/European thinking. I had never heard of the 1" per gallon rule until i started using the internet and found it mainly advised on US based sites.

There is no hard and fast rules for stocking, im sure no one would be really shocked to see a 20 gallon tank with 30 neon tetras in it but if the same tank had two 10 inch Cichlids in it the tank would be grossly over stocked. It all comes down to common sense and what looks and more importantly feels right, the 1" per gallon rule stops newbies from making mistakes but once a little knowledge has been attained there is nothing wrong with bending the rules providing the fish remain healthy and stress free.

CFC,
I first heard the inch per gallon rule in 1995, when I set up my first tank, so I think it'll be based on UK gallons, it wasn't until I went onto international forums like this I heard everyone talking in US gallons, and I still can't get my head round everyone talking in gallons rather than dimensions!!

 

[nmonks]

I haven't read that article, and I don't really like to comment on the work of the other people in the magazine.

What I will say is that I don't think the _volume_ of a tank has anything to do with its stocking capacity, except so far as providing space for a fish to swim in and express its normal behaviour. What determines the capacity is, in my opinion, firstly surface area, and secondly filtration.

When I started keeping fish, the idea was 10 square inches (not 10 inches square, i.e., 10 inches by 10 inches) per inch of small (neon/guppy) sized fish. Realistically, you'd have to double that for medium sized fish like gouramis and angelfish. So, a tank 12 inches by 24 inches gives you 288 square inches. Divide than by 10, and you get 28.8 inches of small fish. In other words, a two-foot tank would hold about 15-20 neons, guppies, danios, rasboras, or whatever, given these fish are around 1.5 inches long.

The logic behind this is that each fish needs a certain amount of oxygen, and given the rate of diffusion of oxygen into the water from the air, it turns out that an inch of fish needs about 10 inches of surface area. When you add turbulence (air stones, filters, etc) they make waves in the surface of the water, increasing the effective surface area. That helps the diffusion of oxygen into the tank, letting you keep more fish.

Why volumes (as used widely in the US, as CFC says) are useless is they don't take into account the surface area. Imagine a tank 12 inches side to side by 12 inches front to back, but 24 inches deep. This has a surface area of 144 square inches. Now imagine a tank 12 across, 24 front to back, and 12 inches deep. This one is 288 square inches in surface area. Both have identical volumes. One can obviously hold more fish than the other, but the volume doesn't reflect that.

As CFC and others have said, these are guidelines. Temperature and salinity have a big influence on how much oxygen water can contain, and the behaviour of fishes may make it more or less possible to stock to a certain level. I do find that aquaria have a certain carrying capacity whatever you do, and if you add another fish, it, or one of the others will die. It's like there's a glass ceiling.

Cheers,

Neale