Join Date: May 2020
Location: Southeastern US
How many corys can I add to my new tank at once?
I just set up my first aquarium since I was a kid at the beginning of April and am about ready to add fish to it and want some advice about how to do so.
I have a 20 gallon long, dirted low tech tank. About half my tank is planted and almost everything is growing pretty well. The tank has been fully cycled for a couple of weeks, but I was waiting out a diatom explosion and adding more plants, so I haven't gotten around to adding with fish yet. I do have 4 nerites that have been in for almost a month that have been going to town on the algae and seem happy. The diatoms seem like they are on their way out and while there is a little green algae growth in certain corners, it seems like it's not growing faster than my snails can eat it. My water is consistently 0 ppm ammonia, 0ppm nitrite, and 5-30ppm nitrate depending on when I last did a water change. I have an aqua clear 30 HOB filter with a prefilter sponge for filtration. My other water parameters (pH, kH, GH, temp) are fine for what I'm planning to do, so I won't go into them.
I want to add a school of salt and pepper corys (C. habrosus). My LFS is going to get some in stock in a week and I really want to add the entire school at once, about 10 to 12 fish. They should be small, ~1/2" each. I know that adding too many fish at once is a classic beginner's mistake and that it is better to add a few at a time to give my filter bacteria time to beef up, but there are some logistical issues that make that tricky. Can I make this work? I have ammonia I can add to the tank in advance to simulate an increased bioload - would that help? If so, how much should I aim for? If you think 10 to 12 is way too many, what's a more reasonable number? I am at home these days, so I can test daily, do as many WC as needed and otherwise closely monitor the situation.
So what do you think? Go for it or tread carefully? FWIW, I won't be adding anything else for a few months.