Rescued guppy with fin nips and lethargic corys

[Freshstar]

Just rescued a guppy with some nasty fin nips, and my corys are acting super lethargic. Tank is a 20 gallon, parameters are 0 ammonia, 0 nitrite, 10 nitrate. Temp is 78F, running a sponge filter and a HOB. Any ideas what's up with them?

[bronzo]

Fin nips could be from stress or aggression. What's your stocking like? Also, lethargic corys might mean poor water quality or low oxygen. You got any surface agitation?

[blueoceans]

I'd check the oxygen levels first. Corys are super sensitive to that. Also, what's your substrate? If it's sharp, it could be bothering their barbels.

[zenox8]

Just rescued a guppy with some nasty fin nips, and my corys are acting super lethargic. Tank is a 20 gallon, parameters are 0 ammonia, 0 nitrite, 10 nitrate. Temp is 78F, running a sponge filter and a HOB. Any ideas what's up with them?

Your params look good, but how often are you doing water changes? Sometimes buildup of dissolved organics can cause issues even if the basics are fine.

[Wildman]

Agree with zenox8. Also, what's the guppy's behavior like? If it's hiding a lot, it might still be stressed from the rescue. Could try some Indian almond leaves to calm it down.

[bertha]

Oh no, poor little guys! I'd definitely add some stress coat and maybe a bit of aquarium salt. Just a teaspoon per gallon to help with the fin healing. And yeah, check the oxygen!

[Globe]

Lethargic corys could also be a sign of internal parasites. Have you noticed any weird poop or bloating?

[prince]

Yeah, parasites are sketchy. I'd dose some General Cure if you're seeing weird behavior. Also, what's your feeding routine? Overfeeding can mess with water quality.

[Freshstar]

Thanks for the tips, everyone. I'll check the oxygen and add some almond leaves. Substrate is sand, so that shouldn't be the issue. Gonna keep an eye on the guppy's behavior.

[reeleech]

How long have you had the corys? Sometimes they just take a while to adjust. Mine were lazy for like a week when I first got them.