Fish Stocking Levels

[-Ian-]

Every fish book or website I've seen before finding this one has used surface area as the measure of the maximum amount of fish you can keep in a tank, just wondered why most ppl here regard volume as being more important instead. My tank is 36x12x18 inches which using the surface area rule (1 inch for every 12 square inches) means I can have 36 inches of fish, and using the volume rule I can have 1 inch per gallon making 27 inches of fish. Then there's this calculator http/www.thinkfish.co.uk/calculators.php?calc=stocking which says with an internal filter I can have 55 inches. I can understand why the type of filtration could make a difference but 55 inches seems waaaaayyy to much for a 3 foot tank. What are your opinions on stocking?

Ian

 

[Tolak]

Stocking is an art, like most arts, learned from hands on experience. If in doubt, err on the side of caution, understock, and work on it from there.

 

[Torrean]

I'm no pro but I think that both volume and surface area are important as well as the width and height of the fishes in question. volume matters because of generic filtration. A tank of X volume usually has Y amount of filtration which means it can process the waste from Z inches of fish. surface area is important because of gas exchange. The more surface are a tank has the more oxygen the water will have. Since the fish need oxygen more surface area means more fish. But I'm usually too lazy to consider all these factors so I go with a basic 1-1.25" of fish per US gallon. Things my lazy self does consider include the messiness of the fish... carnivours need more filtration therefore they need more volume unless you are overfiltering. and width of the fish. if the fish is wide bodied like a puffer then I reduce the general rule to about .75 to 1" of fish per US gallon. So guys what do you think of my methods...total crap right. I kinda just posted them to see what others thought of them


EDITED to agree with tolak since I was typing when he posted. =)

 

[Tempestuousfury]

You also have to realize that it's a matter of both water quality and freedom of movement. So, while surface area is used to calculate O2 and CO2, volume might work more along the lines of space or perhaps nitrogenous waste readings. And, of course, the internal filter increases surface agitation, facilitating gas diffusion and thereby increasing the number of fish, provided nitrogenous wastes, pH, etc. are acceptable.

As stated before, it is more a matter of guessing and checking, and there is no real precise way to limit the "inches of fish" you can have in your tank.

 

[dwarfgourami]

I would not rely on the thinkfish calculator anyway. I ran a couple of possible setups, with fish I have experience of, through that when it first came up for discussion, and the numbers it suggested seemed far too high judging from my experience of the needs of those particular fish. Best play safe, and understock rather than overstock. The inch/gallon rule if used with a long line of provisos can be a help to this. Provisos such as:

it only applies to slimbodied fish with an adult length of not more than 3-4 inches.

some fish need to school, so you can't keep just one or two

other fish are territorial so cannot be kept with their own species, or with fish that look like their species, or with two males together- or whatever (depending on individual species)

some fish are fast swimmers so need long tanks with open areas

some fish are timid so can't be kept with very boisterous tankmates

other fish fin-nip, so can't be kept with long-finned tankmates

some fish are heavy waste producers so you have to allow more space

not all fish are compatible temperature-wise

some fish have different water requirement

a tank can be overstocked even if not fully stocked by inch/gallon rule if all fish live at the same level, e.g. all surface dwellers