Tropical Fish Keeping - Aquarium fish care and resources

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Fishingtons 01-13-2010 12:29 AM

Hi everyone, this is my first post and thread. I have been keeping a ten gallon aquarium for about 5 months now. I've tried to research as much as possible and take the best care of the fish that I could. For most of the five months I had been keeping 3 spotted corydoras and 6 zebra danios (glofish). I have been performing 20-25% water changes every week. I have been doing occasional water testing (1-2 per month), my water conditions have been excellent for most of the life of the aquarium. I have also added appropriate amounts of aquarium salt during each water change. I have had such good experiences with this tank that I decided to start another 29 gallon tank. I keep both my 10 and 29 (currently uninhabited) tanks at my house in the city in which I go to college but I brought my 10 gallon and my fish home to a different city. While I've been home, I found a store with beautiful fancy guppies that I could not pass on. I bought 6 and put them in my 10 gallon with the intent to keep them there for no more than 1 1/2 weeks before placing some of the fish in my other tank. I have been told to strictly follow the 1 inch per gallon rule and have been mostly compliant. However, even with the 6 guppies, 6 zebra danios, and 2 corys (1 died as a result of stress from the trip I believe) my tank actually does not 'appear' crowded. Actually the guppies and glofish are quite beautiful together. My question is this: is my tank dangerously overstocked? I will separate these fish soon if they are but I would prefer to keep them in their current condition if they are not.


If the tank is overstocked then I will remove the glofish and the corys and make my 10 gallon a guppy only tank. I have three pregnant females and I was hoping to try to raise their fry. How many guppies can I safely put in a 10 gallon tank? Again I am familiar with the 1 inch per gallon rule but I have seen many guppies (10+) in much smaller confines than a 10 gallon tank and I have also heard an extreme case where someone had nearly 100 in a 10 gallon (I have no intentions of coming close to that).

Thanks for your help.

MOA 01-13-2010 02:13 AM


DISCLAIMER: Not everyone agrees with my views on fishkeeping or stocking and it would be prudent to wait for more people to respond than just me before making any decisions.

Okay, first order of business: Aquarium salt is not very beneficial long-term. It can be useful when first stocking a tank or when medicating a tank, but the bottom line is that freshwater fish are just that--freshwater fish that should have freshwater. Granted, the salt, in moderation probably won't result in any serious complications, but it won't help either since the concentration is so low. Another thing to consider is that most of the freshwater fish that have lived to record ages did so without many aditives in the tank, including salt.

As to whether or not the tank is overcrowded/overstocked, that is going to depend on who you ask and what you define as being ideal. By many standards I have seen (believe me, I've researched many), your tank is definitely overstocked. Your tank exceeds the inch-per-gallon rule (use the adult length of your fish when making calculations) and it also exceeds the twelve square inches per inch rule. These are the two most common stocking guidelines. However, my one area rule, Joseph Levine's (biologist), your tank is okay. No less, all of the above rules do not account for many factors like tank cleanliness, adequate filtration, compatability of the fish, etc.

Some aquarists prefer to judge the suitability of a system by measuring the nitrogen compound content (ammonia, nitrite, and nitrate). They essentially believe that so long as the fish get along with each other and the nitrogen levels are low, that the system is just fine. One of the problems with this stocking view is that it can push the aquarium to the point where anything that goes wrong can have drastic consequences. For example, if the power goes out on a tank whose nitrogen levels are kept in place by frequent water changes and high levels of filtration, then the aquarium may not last very long on its own. Simply, if you push an aquarium system to its maxium, then the margin of error will be fairly small.

I, on the other hand, prefer to use a combination of factors to assess whether or not an aquarium is overstocked/overcrowded. You can check out my views on stocking on my stocking website, http:/ But the short version is that I do not think that your aquarium is necessarily overstocked. Also, I used to breed guppies and I've had more than 100 in a 10-gallon tank before, but with daily water changes and a back-up generator.


MOA 01-13-2010 02:55 AM

Angel079 01-13-2010 09:24 AM

First of Welcome to our Forum :-)

Salt usage: That's dang dangerous to the Corys (and more likly why one died on you) stop using it.
What I would do if this was my tank; Move the Danio to the other larger tank, they're very active big swimmers and they can't do much of that in a 10g tank. I'd also move the Cory over and up the Group size to at least 6, rather 8. They feel much more secure and are more active in larger groups as that's the most natural thing to them.
That'd leave your Guppy in the 10g. Why I'd not find that overstocked necessarily...Guppys breeding like Bunny's will make this tank soon overstocked with all the fry; unless of cause you purchased all male Guppys?

Fishingtons 01-13-2010 10:40 AM

I should have specified about my guppies. I have 3 males and 3 pregnant females. Thanks for all the responses!

The reason that I wasn't going to increase the number of corys is that if I increased their school to around 6-8 in my 29 gallon, then by the inch per gallon rule my tank would be near capacity. My plan was to also have neon tetras, zebra danios, and possibly 1-2 dwarf gouramis. I'll look into your website MOA. Thanks again for your help everyone and I'll consider upping the size of the cory school.

Oh, and I'll stop using salt. Thanks.

Angel079 01-13-2010 02:18 PM

Scrap that inch per gallon crap.
There's fish that live on the bottom, in the middle and top. Then there's aggressive fish and peaceful ones. Then there's fin nipper and then there's fish that don't get along for various reasons ~ All this tossed the 1fish/gallon right out of the window.

Take my word for it I'm working on the 12th set up here by now, I sorta learned my way around fish by now :-)

So IMO the following would be just fine:
6-8 Julii Cory
2 Dwarf Gourami
School Neon Tetra's (permitted you have SOFT water); and since you already HAVE the Danios, I'd suggest move these heavy swimmers to the 29 and the Tetra (if you have soft water) to the smaller tank and maybe some ghost shrimp for the bottom of the small tank.

Fishingtons 01-13-2010 02:21 PM

Is there any trick to getting softer water besides using reverse osmosis water (thats what the LFS guy said)?

iamntbatman 01-13-2010 04:14 PM

RO is probably the most effective way to soften water. You can introduce acids to the water, which will help soften things a bit but will also lower the pH. If you do this, you'll want to do it very gently. Things like natural tannins from driftwood and peat are a much safer choice than products like pH Down.

Angel079 01-13-2010 05:45 PM

Ro really only proper thing to keep from fluctuating up & down, these chems you see at stores are pretty bad for your fish.
Exactly what is your water (ph & KH)??

MOA 01-13-2010 05:57 PM


I would not worry too much about how soft the water is. I've kept neon tetras alive and well for half a decade in water with a hardness of 300ppm and pH of 8.4. I find that water cleanliness and having a suitable buffer (gypsum works well in most cases) negates most water chemistry issues. The exception, of course, is breeding endeavors as the pH and hardness can have a drastic effect on the eggs of most fish species.

If you are curious about water chemistry, here is a link to some info that I and some other aquarists put together a while back: Water Chemistry for New Aquarists (Taken From MOA's Keeping Fish) (MOA's: How Many Fish?, Stocking Freshwater Aquariums).

As before, note that not everyone is going to agree with me. Some people feel that water chemistry is a major concern. I, on the other hand, used to sell fish and saw more fish die because the new aquarist paid more attention to water chemistry than to more critical issues (like water changes, patience, stocking very slowly, etc.).

If you want a tetra that is not quite as sensitive as neons, then you might look into flame tetras. Flames are one species I have never had sensitivity issues with--hardy fish.


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