Albino cory's get about 3" at adult size. Keep that in mind. You should only add more fish when your tank has cycled. Your next purchase should be a "complete" test kit, that has reagent tests(test tube and liquid chemicals that you drop in)for pH,ammonia,nitrite and nitrate. DO NOT add anymore fish until the aquarium is cycled. Feed sparingly at this time. Usually ammonia is detectable within 4-10 days. Usually after it is first detected, it spikes overnight. It can go from .25ppm to 1-2ppm overnight. Higher if you don't change a little water or use something to cut down the ammonia saturation to no more then 1ppm. You may have to do several partial water changes (PWC's) daily to keep levels in check. Keep a watchful eye on pH at this time also, this is important because pH can dip down when ammonia is spiking. Adjust with baking soda or PWC's to keep pH from falling below 6.8ppm. Reasoning is if the water becomes too acidic it will kill any bacteria that has started to grow and your cycle will never evolve. When you notice that the ammonia levels are starting to decrease by themselves test for nitrites. When nitrites start to build they will also spike in a few days. At this time keep an eye on ammonia levels also, try to keep thembelow 1.0ppm. Sometimes the ammonia spikes again and it will kill off the second batch of bacteria. This will again stall you. Nitrites will spike high but the good news is nitrite can be somewhat de-toxified by adding salt. Eventually the nitrites will zero out. Check nitrate levels. They should come in low 5-10ppm and over a week or 2 get towards 40ppm. When ammonia and nitrites are no longer detectable and nitrate is you have cycled and can safely add fish. I should have mentioned this earlir but also check for nitrate in your tap so you are not fooled by its presence. Some tap water has a good amount of nitrate allready there so frequent PWC's may have to be done to keep it in check. Nitrate over 45ppm starts to become toxic to fish. Anyway with the the 3 cory's in a 10G I would just go with maybe 1 betta or 1 dwarf gourami or a school of 8 small tetras. Or anything you like that is small so not to overload. Platy's and guppy's are nice, but if any fry surrvive they can overpopulate.

I have to mention I too have a 10 gallon Nano cube aquarium. It takes a bit longer to get a smaller aquarium to be stable then a very large aquarium. Don't be surprise in the process if you lose a fish or your aquarium has brown algae. This is all in the process of a new aquarium. If you are still having problens with balance after 4 to 6 weeks, consider how hard your water is through testing. The most important thing is to test your water daily until it is cycled. If you have re-occuring problems that are not being resolved, check the internet or your local fish store for more information. I had a problem with very hard water and ended up getting an Aqua Pharmecuetical tap water purifier to get rid of the brown algae. I have had my 10 gallon aquarium with 2 angelfish and one Tetra for over a year and now I want to go back to the large aquarium. I use to have a 70 gallon aquarium for over 5 years and now miss it after 8 years. I am looking forward to when I get a 100 gallon aquarium. I thought I was really over with this hobby but I guess once you are hooked, you are forever hooked with line and sinker. Ha!
Theresa

You are very limited as to what you put in a 10. angels are NOT recommended for a tank this small. I cant even put angels in my 20, its far too small as well.

You may want to try some guppies, swordtails, neons, danios or other small fish. remember the rule of thumb '1 inch of fish per gallon of water'.

A 10 gallon tank would be a perfect habitat for a male betta. A betta, a few neons, your cories and a snail or two would make a lovely tank :)

i have been keeping fish for almost 20 years now and have NEVER tested my water, as long as you dont overcrowd, never add fresh from the tap water and have a good balance of fish/plants you should be fine :)

The 1 inch per gallon rule applies only to slim bodied fish... like danios, neons, etc... when you start changing the fish body type, the rule doesn't apply.

Theresa wrote when she started up her 10 gallon... and realized her mistake too late. Her water conditions were such she really needed testing in order to control it in the appropriate manner (extremely hard water) Hmmm... as a matter of fact I think it was during the winter when the pond was sleeping that she got the fish bug and brought home the 10 gallon to begin with! LOL

Personally, I don't check my water consistently - essentially I'm of the same belief - less crowded tank is easier to care for, maintains balance more easily. But perhaps I'm luckier than some that my local water from the tap is simply more conducive to fishkeeping? This is not so in all parts of the county and does require more work. The other trick is definitely not to overfeed, and let the tank fast for a day once a week.

I have a 12 gallon that's been going for nearly 5 years now... there have been some fish deaths through the years, but I keep on average only about 6 - 7 fish in this tank. Dwarf gouramis, cory cats, glass cats. The gouramis got replaced simply because pretty much reached the end of their lifespan; a couple of cories got caught in a moving decoration (they were very small babies) - so they had to be replaced.

I usually only test my water on established aquariums once a month or so unless I suspect a potential problem. In planted aquariums w/CO2 injection I check the KH and pH to monitor the CO2 saturation (I lost a pleco by making a mistake before, CO2 was 50+ ppm). New aquariums, or ones I am cycling I check daily, sometime twice a day. Depending on your water supply "advanced" or sensative fish like Discus need daily testing. Neon Tetras ( and most small tetras) are not good to cycle the aquarium with but are a good fish in an established 10G.

The inch per gallon rule is really more of a guideline. Amount of food, size of filtration, and frequency of water changes are hugh factors in water quality. The smaller the tank the quicker things can go south so buy as big a tank as you can. For FW after cycling PH and ammo tests are good indicators of water quality.