A Newbies Basic Guide to the

[OohFeeshy]

So, you have a new tank. Obviously it needs to be cycled, read up about this in the FAQ section if you're thinking 'Eh?'. Then you're going to want some fish in there.

The most basic guideline for stocking is the famous '1 inch of adult fish per gallon of water'. This basicly means that for every gallon of water your tank holds, you can have 1 inch of adult fish, not including the tail. The guideline is intended for US gallons, but for litre users it roughly translates as 0.6 cm per litre (based on 2.5 (1 inch into cm) divided by 4.5 (litres in a gallon))However, there are many exceptions.

1) This only really applies for smallish tanks, not sure the max is can be used sensibly for, but it is mainly used on tanks 30g or less.
2) It only aplies to smaller (ie, adult length less than 5 inches), slim bodied fish of average waste output, aggression and activity level, for instance, tetras. By this I mean that, to take a few examples, even though danios get to about 2'', they need a tank of 20g plus due to their activity levels. Dwarf puffers, even though they are very small fish, need about 5 gallons ech because they are so messy. It would be silly to put a 20 inch fish in a 20g tank, but much more sensible to go with 10 2inch fish. This is the most complex exception to explain really, but as a guideline, the main two groups of fish to use this with are cories and tetras. I might do another topic explaining this properly, but you should (hopefully) get the idea.
3) It only applies to adult length. I said this above, but you wouldn't believe the amount of people who think that they can put something like 20 1 inch silver sharks in their 20g tank. Fish grow, sometimes by a little, sometimes by a lot.

There are plenty more but this covers the basics of that guideline. When I get home tomorrow I'll add more to thi on another stocking method, feel free to add advice about the inch per gallon guideline and I'll bung it in later.

 

[pica_nuttalli]

this rule also only really applies to slim-bodied fish with an adult length under 5 inches.

 

[boxman]

That rule is a rough guide as has been pointed out - it was made up for the US gallon rather than the larger imperial/UK gallon.

As with everything there are exceptions to the rule - puffers (and many other fish) require at least 5gal as they have terrible table manners and get food everywhere where as a betta is OK for a short period in a betta breda which is only a few inches (not recommended for long periods of time!)

Possibly a pinned topic comming up I feel!

 

[OohFeeshy]

Ooh, pinned I'll add your info, duh, forgot it was for US gallons )

 

[sylvia]

This would deffinately be a useful pinned topic... I suggest you change the title however to something along the lines of 'How many fish can I keep in my tank?' so that newbies who see it click on it (most won't know what the 'inch per gallon guideline' is when they start out).

There are many exceptions to the guideline. You've hinted at some of them but I'd like to add a few more common ones...

With some fish, like mbuna cichlids, over-stocking is reccomended and even necessary. This is because keeping several of these territorial fish reduces aggression towards any one individual by splitting attention up.

Simialrly, most common livebearers have to be kept as trios so the inch per gallon guideline has to be applied with this in mind.

Many of these fish also have males which are considerably smaller than females. The average size given in most books or internet sites, in this sense, may be mis-leading.

Also, tall tanks can hold fewer fish than long tanks because of the smaller surface area to volume ratio which allows less oxygen to get in.

Some fish, like danios for example, also need to be kept in a group because they are schooling fish. The same applies to most tetras, rasboras and barbs.

Other fish, regardless of size, should only be kept one to a tank - such as red tailed black sharks or male bettas.

Extra filtration or live plants can also increase bioload capacity but will not, obviously, offer more physical space.

Another consideration when it comes to stocking is water temperature as less oxygen can be in warm water than in cold.

Basicaly, the inch per gallon guideline is not set in stone but it's a good guideline for beginners. Don't base your choices strictly on this.

However, I would say that the most important thing to remember is that, though all baby fish start out pretty much the same size, some only about double in size while others grow into monsters. NEVER impulse buy or trust your LFS to give you the adult size. Research everything yourself and don't just check size but also compatibility, environmental requirements, feeding requirements and the ratios they need to be kept in.

 

[OohFeeshy]

I won't edit that in, I'll let you take the credit