CarmenA Posted December 28, 2020 Share Posted December 28, 2020 Hi I'm new to this forum and to aquariums. I have a 15 gallon high tank. It's been running for about 2 years. Lately my Cory catfish has been gulping air at the surface. So I figure I need to add an air stone. I just ordered a sponge filter and stone that should arrive in a few days. The tank has a hang on filter now. My question is should I run both filters or just the sponge filter? There's only 5 fish in the tank , swordfish, molly, tetra, peco and the cory. You're help is appreciated 1 Link to comment Share on other sites More sharing options...
Mitch_ScruffyCityAquatics Posted December 28, 2020 Share Posted December 28, 2020 Cories gulping air isn’t always a sign of stress. I’ve read they have been known to do it even when the water is highly oxygenated. Some say they do it after a good meal. It could be due to stress. Corydora are schooling fish. It would be happier with a couple of friends, and happiest with five more. The same could be said for the tetra. It may be fine, but if you see any signs of stress that is probably why. I have two air stones and sometimes I see (or hear) my cories hit the surface. But I do think an air stone is beneficial for all aquariums. So I am not trying to discourage the use of one. If you want to replace your HOB with the sponge filter I would leave them both running for a few weeks until the new sponge is seeded with bacteria. You can help it out by squeezing your old filter media next to the new sponge. It will make the tank cloudy for a few hours, but it helps. If you aren’t worried about energy consumption you can run them both. Link to comment Share on other sites More sharing options...
Andy's Fish Den Posted December 28, 2020 Share Posted December 28, 2020 Corydoras will swim to the surface and gulp air and go back down to bottom. It's a normal behavior for them. I have actually had a cory end up out of the tank from swimming to the surface so quick and it jumped and landed outside the tank, so make sure there are lids on your cory tanks. 1 Link to comment Share on other sites More sharing options...
CarmenA Posted December 28, 2020 Author Share Posted December 28, 2020 Thank you both for the info! If I put 4 more Corys and tetras in the 15 gallon tank would that over crowd it? Link to comment Share on other sites More sharing options...
Andy's Fish Den Posted December 28, 2020 Share Posted December 28, 2020 8 minutes ago, CarmenA said: Thank you both for the info! If I put 4 more Corys and tetras in the 15 gallon tank would that over crowd it? No, you'll be fine. 1 Link to comment Share on other sites More sharing options...
CarmenA Posted December 28, 2020 Author Share Posted December 28, 2020 Thank you to Petsmart I go! 1 Link to comment Share on other sites More sharing options...
Aqua junky Posted December 28, 2020 Share Posted December 28, 2020 I absolutely love my Cory's! I've got a 40G half moon dedicated just to Cory's and kinda a grow out tank for a few Loachs! Most interesting fish in the hobby! 1 Link to comment Share on other sites More sharing options...
Mitch_ScruffyCityAquatics Posted December 28, 2020 Share Posted December 28, 2020 1 hour ago, CarmenA said: Thank you both for the info! If I put 4 more Corys and tetras in the 15 gallon tank would that over crowd it? A 15 tall has the same footprint as a 10g. For most Cory species I think a school of six would be more comfortable in a 20 g. There is more space on the tanks substrate. I’m a little worried five would be crowded and that may cause stress (which is the reason you are adding fish). It may depend on what you have on your substrate (ornaments, decorations, plants). You might try adding two more and see how they do with three. If they try to hide a lot, your parameters are doing well, and you feel like there is still room you could try adding some more. You should be 100% ok with the tetras though. I’d put six in there, for sure. Link to comment Share on other sites More sharing options...
CarmenA Posted December 30, 2020 Author Share Posted December 30, 2020 Well I bought 3 little Cory's a nd 3 barb tetras and my Cory didn't seem to change his ways. This morning I setup the small sponge filter and air stone and bam he's a happy camper! swimming around eating and hardly going to the surface except to grab some food. Thanks for all of your advice everyone! Now for another question. I'd like to get a larger tank. Any advice on manufacturers, acrylic verses glass etc.... Thanks Carm 1 Link to comment Share on other sites More sharing options...
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