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Hello Cory lovers! I'm new here, but not to fish keeping. I've grown up with cories in the family fish tank, and have kept panda cories myself. But since then, I've planted all my tanks and wonder what you pros think about this:

A friend of mine wants to rehome 5 adult orange laser cories. I would love an opinion about housing them in my 40g long.

Tank dimensions: 4ft long by 1ft front to back and 18" deep
Filtration: Eheim 2215 and two internal filters for circulation
Lighting: one or two 65k HO T5s (the tank still has a bit of long hair algae I'm dealing with)
Substrate: organic soil topped with pool filter sand/fine gravel
Fauna: 18 rummynose tetras, a few amano shrimp
Flora: hygro agustifolia, mermaid weed, baby tears as a foreground, java fern, fissidens moss, crypt wendtii

There is a bit of driftwood for caves, but the tank is mostly plants.

The thing I am concerned with is I added pressurized co2 on the tank a few months ago. I leave it on continuously, but it's below 30ppm. The fluctuations in pH are more stable that way. At night the pH will drop to 6.8 and at the end of the photoperiod, it's 7.2

Any thoughts about this tank? Or would they be better on their own in a smaller (say 18g @ 2' long) without pressurized co2?

Thanks!

I am not an expert but I had a lot of cories in a planted 125 with co2 and they did very well.

They'll be fine.

Thanks everyone. I've decided to get them and they are acclimating to my tank. At first they were not active at all, they just hid and sat on the substrate. After a few hours, they have started to explore and mimic the rummynose tetras a bit. I assume this is normal behaviour? And also, the pH fluctuations are not as extreme as I had thought. It seems to have settled in the 7.2-7.4 range.

angelcraze wrote:Thanks everyone. I've decided to get them and they are acclimating to my tank. At first they were not active at all, they just hid and sat on the substrate. After a few hours, they have started to explore and mimic the rummynose tetras a bit. I assume this is normal behaviour? And also, the pH fluctuations are not as extreme as I had thought. It seems to have settled in the 7.2-7.4 range.

Hi, just to put your mind at ease a bit. PH fluctuations from CO2 injections have no bearing on the KH, thus do not affect fish at all. So that shouldn't be an issue. The more dangerous is dumping fish into a high CO2 level tank without allowing for an adjusting period, and obviously CO2 dumps due to accidents. Hopefully they are fine. Corys are tough fish.

Thank you! It does ease my mind, the kh is something I didn't even take into consideration! I always let any fish acclimate, so that was not an issue either, thankfully. I think they're happy, there has been two batches of eggs since I got them!

angelcraze wrote:I think they're happy, there has been two batches of eggs since I got them!

Congratulations! Like I always say, "A spawning fish is a happy fish!" (okay, so maybe that's not ALWAYS true; but just for a moment, let's revel in anthropomorphism! )

Cheers, Eric