Stocking Questions

[pahansen]

Hi. I am looking for some detailed information/"expert" opinions on stocking levels for tanks. For my purposes, people who are just going to say "one inch of fish per gallon of water" need not apply. (No offense intended to anyone.)

I have tried to find some detailed information about tank stocking. So far I've found a good table at http/www.thetropicaltank.co.uk/tanks-us.htm, which uses the surface area calculation for stocking, and a good article at http/www.fishdomain.com/tank_stock.shtml. Other suggestions are welcome.

I have a healthy planted tank, 20 US gallons, 24'x12"x20" (water is a bit over 12" deep), which is currently as populated as I would like to see it. Some of my fish were intended to go into a larger future tank when I bought them. The big question is when to make the move.

Right now, according to the chart I mentioned above, we are just about at the maximum (24") of fish, some of which are still growing. But we have one fish (the African Butterfly) who is a surface only fish, and two fish (a small pleco and a weather loach) who are almost exclusively on the bottom of the tank. A few of the articles I read seemed to imply that having fish who lived on different "levels" of the tank was beneficial to the stocking levels. And of course, the plants are beneficial as well.

I also read one article where the author said that the maximum size fish he would have in his tank was no more than 1/6 the length of the tank. Does this seem like a reasonable rule of thumb? It does seem to make sense from the standpoint that the fish need space to swim. According to that idea, we would probably be moving to a larger tank in about 6 months (at 4"), assuming the pleco keeps growing at the same rate he has been.

Basically, I have had no problems so far with my nitrate or nitrite levels, and the pH, hardness, etc., have also been stable. I just don't want to wait until I start having problems before I upgrade. I would like to start shopping for larger tank a month or two before I need it, just so I can try to find a good deal. And of course I would hate to stunt my fishes' growth by keeping them in a tank that's too small -- although I think we're still quite a ways off from that. I'm just trying to balance the outlay of cash with how soon we will need a new tank.

Thanks for your help.
-- Pamela

 

[sylvia]

I am not an expert but I do have opinions

For a start, using 'rules of thumb' like keeping fish 1/6 the length of your tank, using surface area and stocking at different levels is not realy going to get you anywhere IMO. I think the only way to tell if your tank is overstocked waste-wise is by monitoring the water quality (especialy nitrAtes and the only way of seeing whether you are over-stocked oxygen-wise (which is the reason for the surface area rule of thumb) is to watch your fish for signs of distress and the only real way to know if your stock is compatible and comfortable is from watching your fish closely on a daily basis and from experience.

The fact is, stocking levels depend entirely on what fish you keep. Looking at surface area, for example, a 4" rosy barb does not have the same mass as a 4" puffer or a 4" gourami. Then with waste, a 10" pleco is messier than 10 1" neons. Similarly, you could keep 4 pearl gouramies in your tank - but try keeping 4 convicts of the same size. You could keep some middle-dwelling tetras with the gouramies - but not with those (remaining ) convicts. What I'm saying is that different species of fish have very different behaviour and produce different amounts of waste and are of different sizes. You can keep 10 cory cats but not 10 rams due to territoriality and you could keep several swordtails but the same number of bristlenoses would add more waste. Your filtration, temperature, equipment, maintainance, feeding etc, all play a part. It is therefor impossible to say that 'this is the rule for stocking - it applies to all fish and tanks and owners'. That's simply impossible.

My suggestion to you is to watch your fish for any signs of trouble (very closely and on a regular basis). At the first sign of a change in behaviour, try to pinpoint the cause and correct it asap. Also monitor your nitrAte levels and when they begin to get unmanageable with your current maintainance routine, increase water changes and also go get that bigger tank. pH can also act as an early indicator of problems so watch this too and try to prevent fluctuations - if you see any minor changes and the cause is not an object releasing chemicals or anything like that, most likely you need to increase water changes and need that new tank.

As for when to get the tank - well get it now.

 

[pahansen]

Hi Sylvia. Thanks for the input. I was basically of the same opinion -- everything depends on everything else -- but wanted some reinforcement for it. I'll keep watching the tank to make sure nothing is out of whack.

I'd love to get a big tank now, but it's supposed to go in our half-finished game room downstairs. We need to un-clutter and recarpet it -- the room, not the tank!, and I don't want to try to set up a tank and move it. We were going to try to have this done by the end of this year, but maybe we'll try to scoot that up to the end of summer, just in case.

And let's face it -- my one 3" pleco outproduces the sum total of the rest of my fish, waste-wise! Good thing I love him!

-- Pamela

 

[Teelie]

And to add to that, you'll want to get your new tank at least one month in advance to set up and cycle it then be prepared to move your fish otherwise you could end up with some severe ammonia or nitrite poisoning problems.

 

[Yenko]

It's true that any rule based on fish legnth isn't right; who seriously thinks that 10 1" neons equals the output of one 10" loach of cichlid?

Aside from weighing your fish there is no accurate way to tell; the best way to do it is to play it safe. It's much more enjoyable to run a healthy, low-maintenance tank with less fish than an overstocked one.

 

[littlefishie]

I'm so glad I read the entire post before I responded.

Sylvia, you beat me to almost everything I wanted to say!

Another thing to consider is the swimming levels of your fish. There's bottom dwellers such as cories and loaches, or even some rams. Middle-dwellers like neons and rasboras, and top-dwellers like guppies.
Check out the direction the mouths of the fish you're interested in are oriented. That should help you figure out where they'd be swimming in the tank.

If you can balance the levels, it'd make a much nicer looking tank and it might be easier to stock.