I've been in the fish hobby for roughly 3 yrs now and during that time one thing I have struggled with is stocking levels. So I thought I'd ask the question "How do you do it?"

I end up adding the total cms to equal the total length but I know thats wrong cos 2 tanks could have the same lengths but totally different widths..

i was told 1 inch of fish per Gallon.

Problem with that is it treats a 4" discus the same as a 4" kuhli loach. It also says I can keep a 12" pleco in 12 gallons (50l).. but only 12 x 1" neon tetras.

A better idea is to allow 1 gallon of water for 1 CUBIC 1" of fish

http://www.monsterfishkeepers.com/forums/showthread.php?t=88431

That gives your 12" pleco 12"x2"x2" = 48 gallons (200litres). Much more sensible.

Neons might be 1" x.5"x.5" = .25 gallon or 1 fish per litre of tank, again more sensible.

Of course this is just a guideline, depends on your filters, water changes and what the particular fish are. But at least it's a starting point. Maybe we need a metric version.

Cheers

Ian

The 1 inch per galleon is only a general guideline, but fails miserably in most cases though.

Depends on what level your fish swim at, the capacity of your filter and of course the size of your tank.

It's only overstocked when nitrates climbs too high between water changes, or if ammonia or nitrite is detectable, then it's definitely overstocked, or you need to upgrade your filter.

I have the following fish in my tank and it seems overstocked (definitely is by the 1in/galleon rule), but weekly nitrate don't get over 25ppm, so it's not really overstocked, plus the fish is evenly decided at different levels.

Have you dont the maths using the cubic inches?

I suspect you will be closer to that guidline.

Cheers

Ian

i generally look at lots of other pictures on the net on what I want my tank like and see what filtration system they have. after a while you get the general idea

It is all relative. Importers holding fish in Quarantine or breeders raising heaps of young will stock up their tanks extremely heavily and get away with it. They generally have bare or at least unplanted tanks, heavy aeration and very frequent water changes. I raise killies in bare tanks with no filtration or aeration successfully. I don't cycle the tank before puting fish in because there is nothing to cycle, feed very heavily and remove excess food frequently, and do very frequent water changes. When they are about half grown they get moved to a more balanced situation in a lower stocked and heavily planted tank (with low filtration and no aeration). If a bare tank was very heavily stocked I would put a sponge filter in there.

I raise killies in bare tanks with no filtration or aeration successfully. I don't cycle the tank before puting fish in because there is nothing to cycle, feed very heavily and remove excess food frequently, and do very frequent water changes. When they are about half grown they get moved to a more balanced situation in a lower stocked and heavily planted tank (with low filtration and no aeration). If a bare tank was very heavily stocked I would put a sponge filter in there.

Thanks for that bit of info, was/is very helpful.

Im about to have a try at killifish and thought I may need filtration etc etc, but you have eased my mind alittle!

Thanks for the input.. Ianab I'm a bit confused on how to work out the cubic " of a fish.. can you give me an example

Also I have a male betta so when calculating his cubic " is it just the body or the fins too?

I'm a bit confused on how to work out the cubic " of a fish.. can you give me an example

OK.. it's just a way of approximating the actual size of a fish - not just it's length.

I used a discus and a kuhli loach for example. Both might be 4 inches long... But they aren't the same size.

Kuhli = 4" long x 1/2" tall x 1/2" wide = 1 cubic inch.

Discus = 4" long x 4" tall x 1" wide = 16 cubic inch.

It's not an exact science, but it does make more sense that you can keep more long slim fish than big fat fish.

I guess if you actually weighed the fish and worked out a rule that way it would be better, but who wants the try and do that :roll:

I think you are better to just keep a few less fish and not have to worry, or over filter and keep an eye on water tests, they will tell you if you have too many fish. If ammonia or nitrite start to go up then you dont have enough filtration for the fish you have. If nitrates climb too fast, then you have too many fish for the tank.

Cheers

Ian

There is no universal formula - in the end it comes down to having the right mix of compatible tank mates and how much maintanance you are prepared to do as much as the actual number of fish in the tank. If you are the sort of person who does one water change a month, stick to a smaller number of small fish - if you are prepared to do large weekly or daily changes and spend plenty on big filters and tanks, you can support more. Finding the balance is largely trial and error (unfortunately), but adding 'just one more fish' is a sure way to overstock and will lead to regular outbreaks of sickness. Remember that a lot of tanks in shops are chronically overstocked and can give a false impression of what is sustainable. There is no such thing as an understocked tank, so I'd recommend spending your money on fewer, but nicer, fish rather than going for sheer quantity.

ok, thanks for the help.

I don't do water tests, but I do have 2 test kits which are a couple of years past their best before dates.. would these still be correct? they are still in original packets.. anyway when I'm really bored I have done a few tests and they were always good..

I have 2 filters on each of my big tanks (100 litre is what I call big cos they're my biggest ) and I'm sure they're doing fine

Just to make sure everything is fine best to buy a set up new test kits and test the water.

Forget all the 1" per Gallon B.S, if your nitrares/nitrites/amonia are good, everyone is getting along and the fish have room to turn around then your stocking level is probably fine. Just look at some of the 'Japanese Style' tanks, has anyone ever tried calculating the cubic inch per gallon of a crazy "overstocked" tank like that? Its probably waaay "overstocked" yet the fish always look beautiful and healthy.

Conch is correct, a lightly stocked tank is MUCH easier to look after. If you miss a water change occasionally, no big deal. If your tank is at the max then you HAVE to keep a good eye on the water quality, there is no margin for error or slack maintainance. You are allways 1 dead fish hidden under a log away from a disaster.

Also you need to think ahead a bit.. sure you can work out your stocking rate and go and buy the fish. But in 6 months they might have doubled in length.. and be EIGHT time the weight, and eat 8x the food, produce 8 time the poo.

The answer is actually simple though.. when in doubt, get another tank 8)

If you are worried you have too many fish for your 100l tank, upgrade it to 200l and keep the same fish. They will thank you for it

Cheers

Ian