Corys Staying At The Surface :(

I have a 29 planted tank that WAS cycled, but something caused it crash and I have no clue what it was so I've been doing 20-40% water changes daily. I had a bacteria bloom this morning so I did a good vacuum and 40% change and added some safe start. This afternoon I'm noticing two of my nine cories propping themselves between my light and the surface of the water and gasping. If I reach in and boop them they swim right back down, then swim up and hover around the surface before swimming down. I don't notice any bloating or pink/red on them. One Cory is an albino and the other is a pepper, both about the same age. All corys have been in the same tank for almost a month.

I also have a pleco and a betta both which are acting fine and so are the rest of the corys.

I just did another 3 gallon water change with Prime and stress guard. Before hand the water was:
Ammonia: 0.2
Nitrite: 0
Nitrate: <3

I know cories are sensitive to nitrate so I'm keeping an eye on it as I do water changes. The pH and temp I'm not worried about because they stay stable. I do have a bubble wall but the air pump is made for 5-10 gallon tanks. I had one that was for 30-40 but it was too harsh for the betta. I think they make one for 20 that I can pick up after work tomorrow morning if oxygen is the issue.

The fish are all active and react when I move near them or poke the substrate with the turkey baster I suck poo out with. I'd rather not lose these cories but I have no clue what else to do right now.

I do have a large bottle of tetra safestart plus coming in tonight and some more prime and garlic guard, just hope they can hold out till then.

The only other chemicals I use is jungle start right (for the aloe) and Seachem Flourish and Iron.

 

Don’t know if this helps or is 100% scientifically but prime can remove a lot of oxygen when it is dechlorinating the water. Your bubble stone bubbles all that off and makes the water fine again but if you are doing more water changes then maybe the bubble stone can’t work fast enough? Try aerating the the water you use the prime on for a good bit before adding it to your aquarium? Also if your ph fluctuates a lot during water changes the corys could be reacting to that. Do what you think you should for your fishies but if your using prime you can do water changes every other day for example, water change one night, test and dose with prime relative to the amount of nitrites and ammonia the next. Then repeat. Just an idea to help increase the stability of the tank environment in an unstable time

 

I'm sorry your fish aren't well. This isn't my area of expertise but I'll try to brainstorm a bit until you get more advice.

Gasping at the surface suggests to me a lack of oxygen or gill irritation (from toxin burns when the cycle crashed or a parasite like gill flukes).

I'm inclined to think it's not an oxygenation issue if the other fish are fine but more O2 never hurts as long as the water current doesn't get too strong. Drop the water level a bit if you have a HOB filter to increase surface agitation and remove any surface film that might be impeding the gas exchange process. Rather than buy another air pump, you might buy a $3 flow valve controller to reduce the impact of your old, stronger pump.

If you use CO2 I'd stop until this is figured out.

I find a cheap magnifying glass is helpful to examine my fish up close. I got a cheap one for maybe $7 on Amazon and use it all the time.

If they have gill damage from the cycle crash that's trickier. Pristine, stable water parameters can only help.

To get your cycle back on track: When you get the TSS I'd shake it really hard, turn off the filter, dump it right into the filter media, let it sit for 30 mins, then restart the filter.

I wish you luck and hope others will have more advice.

 

I'm sorry your fish aren't well. This isn't my area of expertise but I'll try to brainstorm a bit until you get more advice.

Gasping at the surface suggests to me a lack of oxygen or gill irritation (from toxin burns when the cycle crashed or a parasite like gill flukes).

I'm inclined to think it's not an oxygenation issue if the other fish are fine but more O2 never hurts as long as the water current doesn't get too strong. Drop the water level a bit if you have a HOB filter to increase surface agitation and remove any surface film that might be impeding the gas exchange process. Rather than buy another air pump, you might buy a $3 flow valve controller to reduce the impact of your old, stronger pump.

If you use CO2 I'd stop until this is figured out.

I find a cheap magnifying glass is helpful to examine my fish up close. I got a cheap one for maybe $7 on Amazon and use it all the time.

If they have gill damage from the cycle crash that's trickier. Pristine, stable water parameters can only help.

To get your cycle back on track: When you get the TSS I'd shake it really hard, turn off the filter, dump it right into the filter media, let it sit for 30 mins, then restart the filter.

I wish you luck and hope others will have more advice.

Oh my gosh I had no idea prime did that! I'm going to pick up a stronger pump after work tonight and take your advice on using prime every other day. I have the jungle dechlorinator I can use too. Thank you for this information!!

 

Could it be the corys aren't simply scavaging the surface (for food)? I think it is "strange" there are only two doing so if it would be a lack of oxygen.

Like these ?

 

Could it be the corys aren't simply scavaging the surface (for food)? I think it is "strange" there are only two doing so if it would be a lack of oxygen.

Like these ?

I've seen my larger ones doing this especially when I feed my betta. But no, these two are wedging themselves between the tank wall and the led bar with their mouths barely poking the surface and just gasping last I saw them.

Cute video tho Omg ❤️

Morning update: no one was resting at the surface when I got home. I plugged in the new air pump and not even five minutes after I started it, everyone in the tank livened up and started swimming like energetic cories! Even the betta started swimming in and out of the bubble wall. (the pleco was nonplussed, but I think it's because I woke him up).

The one albino Cory that was acting oddly is still acting oddly though, but I notice his gills almost look inflamed. He seems to be struggling with swimming at times. Besides the irritated gills he looks unharmed and healthy. I'll keep an eye on him for now, it could just be he got irritated on one of the plants.

Everyone else is acting normally. Thank you again for the info about prime and how it effects the oxygen!!

 

Morning update: no one was resting at the surface when I got home. I plugged in the new air pump and not even five minutes after I started it, everyone in the tank livened up and started swimming like energetic cories! Even the betta started swimming in and out of the bubble wall. (the pleco was nonplussed, but I think it's because I woke him up).

The one albino Cory that was acting oddly is still acting oddly though, but I notice his gills almost look inflamed. He seems to be struggling with swimming at times. Besides the irritated gills he looks unharmed and healthy. I'll keep an eye on him for now, it could just be he got irritated on one of the plants.

Everyone else is acting normally. Thank you again for the info about prime and how it effects the oxygen!!

You mentioned a bacterial bloom. The bacteria involved also use oxygen. It might be some events came together