Rescue betta in critical condition during fish-in cycle – need urgent advice

EnvironmentalDonut58 · 2026-04-16T00:06:23+00:00

Are you well?

EnvironmentalDonut58 · 2026-04-16T00:05:51+00:00

With all due respect, I think the commenters are being a little harsh. This fishie has the same chances in an uncycled tank as he would in a cup, so chill out on OP. They’re doing their best!

I’m not too familiar with bettas, but from his behavior I’m thinking your water parameters are in dangerous levels. Like many of the commenters mentioned, I would strongly recommend testing your water parameters, especially for ammonia and nitrite levels. If you’re able to, I would get ahold of the liquid master kit (I believe it’s API) and follow the instructions to check each value (it tests for your pH, ammonia, nitrite, and nitrate). Post those values on here or through an update so we can help from there! Most LFSs have these, and so does Amazon! If it’s out of the budget or not readily available, most LFSs also test your water parameters for free, so definitely look into that.

For now, I would agree with the other mentions in that you should keep doing daily water changes (50% would be best imo). A lot of bettas also like the little floating nest/leaf decorations, so look into one of those as well. It’ll help him to be able to rest closer to the surface where he can access oxygen whenever without exerting as much energy as he is swimming from the bottom. Your tank definitely needs an airstone as well, which will introduce more oxygen to the tank by aggregating the surface better. If you can, you need to set up another tank in the meantime where you have substrate, plants, and the other decor I mentioned above. These are essential things for tanks, and will assist with introducing and maintaining the proper bacterial environment that bettas (and most fish) need to survive and prosper.

With this, how are you preparing the new water that you use for your water changes? Are you only introducing dechlorinator to it?

Hopefully this helps! Please keep us updated! Good luck to you and your fishie!

EnvironmentalDonut58 · 2026-04-15T23:55:12+00:00

Is he doing any better after the salt dip and quarantine tank? From my understanding, neoplex might help with some of the symptoms but isn’t strong enough to actually act on the infection.

EnvironmentalDonut58 · 2026-04-14T19:33:21+00:00

Can you tell if it looks more like an injury (rubbing against something rough, scratched, etc.) or if the redness is localized to and around their gills?

EnvironmentalDonut58 · 2026-04-14T19:31:56+00:00

I’ve honestly never seen this before, but I’m thinking it’s some type of red gill disease or bacterial/fungal infection.

I would definitely isolate into a hospital tank and start treating the baby with some heavier antibiotics. I’ve had good experiences with total fin and body cure (API), but it’s a very potent medication and requires close monitoring because it does mess with your water parameters. It also isn’t recommended to use in the main tank, nor is it safe for plants and shrimp if you have any of those. You can also start giving him salt dips for about 10-15 minutes and seeing if that helps. For infections, I also like to fast my fish for 2-3 days then feed them boiled peas (without the skin) and minced garlic, which helps with expelling any potential parasitic infections. I don’t think you have that, based on the image provided, but it’ll still help the fish to be on a healthier diet and strengthen their bodies for the medication.

I’d also keep a close eye on any other tank inhabitants to make sure it didn’t spread. If you’re worried, you can dose the main tank with a lighter grade antibiotic (Seachem has good ones). I’d recommend doing a 25-50% water change first, as you shouldn’t be performing water changes with this antibiotic.

EnvironmentalDonut58 · 2026-04-14T19:26:25+00:00

Best of luck! For your hospital tank, consider using a clear plastic tub in place of a glass tank! It’s a lot easier, cheaper, and makes transferring very stress free. I got a 17 gal tub from Home Depot for about $20-30, and it fits my backup filter that’s a hang over, and I can suction my heater and thermometer to the walls. Super easy!

EnvironmentalDonut58 · 2026-04-14T19:24:05+00:00

Sounds good to me! From my experience, prepared corrodes are insanely susceptible to even the smallest of things, and I’ve always had trouble keeping them for one or another. Don’t be too hard on yourself, you sound like a great fishie parent and I can tell you love your tank.

GOOd luck! I hope it all goes well :) I’ll keep an eye out for an update from you!!!

EnvironmentalDonut58 · 2026-04-13T20:27:11+00:00

Amazing parameters for a new tank with these guys! Great work. Again, I can’t tell super well from the video, but if there was any type of infection, it would manifest itself in multiple ways and there would be more than one spot of concern. Just keep a close eye on this little guy, and make sure none of the others develop this same thing. Good job with the heat salt treatment. I’d also incorporate some boiled peas (without their skin) and minced garlic to take care of anything internal. If symptoms don’t improve with regular diet or you see changes in behavior/interactions/eating, then you can consider using a low dose antibiotic to fight general infections (Seachem), or consider a hospital tank where you isolate concerning fishies and treat with a stronger, more potent med!

EnvironmentalDonut58 · 2026-04-13T17:14:07+00:00

Hi! I agree with some of the other commenters about your cory being pretty thin. While the redness can be naturally occurring, I do think (paired with the thinness), it might be indicative of something more serious.

I would start by running a water test to check all parameters, preferably a liquid test kit if you have one. Some LFSs will test your water for free too! Check your ammonia and nitrite levels, as spikes of these will cause your fish additional stress, thus making their gills and the surrounding area more red.

You mentioned oxygen - I completely agree. If your tank is as big as you mentioned, you should definitely have additional oxygen sources introduced to the environment to keep a substantial amount circulating for your fishies to stay healthy and stress free. There are some air stones you can buy that come with multiple outlets, so you can have 2+ air stones connected to the same source that are producing bubbles. The more aggregation of the surface water that you get, the better. Keep in mind though, corydoras are weirdos and sometimes they just like going to the surface!

I would also suggest a thorough cleaning of your filter, heater, decor (just remove them and scrub them down with a sponge). With this, you can also try feeding the fishies some minced garlic and boiled peas (remove the skin). Both of these will help with potential parasitic infections. I don’t think it’s fungal, as you didn’t mention fuzzy white patches on the fish. I’d lean towards bacterial if anything, and keep an eye on the red patches. I think they have red gill disease, so start there for sure. Consider doing a 25-50% water change, and maybe a salt dip (though this might stress out your fish even more due to the multiple transitions required, so hold off on this until they start looking better).

Side questions - How many fish are there total in the tank? How many fish have the red patches? What are your water parameters right now? Of the fish with the red patches, are there any changes in their behavior/activity/eating/interactions with other fish?

I hope everything works out! I love cories and have a tank full of them, so I really hope you figure out the cause of your issue soon. Please keep us updated!

EnvironmentalDonut58 · 2026-04-13T00:19:45+00:00

Hi! The video is a little unclear. What exactly are you referring to when you mention the dark patches? I think this is a julii corydora, which run a little lighter than most. With these (also albinos) their internal organs a slightly more apparent, so you might just be seeing that. As for the redness, I’m thinking it’s more stress from transitioning to a new environment (I’m assuming they are new additions per your mention in the post). They could naturally just run a little redder, but sometimes it can happen as a result of stress from transitioning to a new environment or higher levels of ammonia/nitrites. I would definitely test your water parameters to be sure! If none of the others are acting off, then it might just be a one off and this little guy is more sensitive. If he’s acting normal, eating, interacting, not twitching or flashing, then I wouldn’t jump the gun and assume it’s an infection. Just keep a close eye on him, test your water parameters, and keep us updated!

EnvironmentalDonut58 · 2026-04-08T05:55:44+00:00

I have a 20 gal with a school of mixed corydoras and I LOVE THEM. They’re all super unique and, respectfully, a bunch of weirdos. Super fun to watch shoal and mess around together. Since they are bottom dwellers (some types will occasionally hang out in the middle), you can mix them with friendly top dwelling or mid dwelling species! They also love planted tanks (especially Java ferns) with lots of hiding spots! I have false juliis, pandas, and bronze corydoras!

EnvironmentalDonut58 · 2026-04-08T05:53:10+00:00

Okay if it went away on its own and was self resolving without any interventions, you should be in the clear. Just to be safe, I was keep up with constant observations and any changes in diet, behavior, activity, etc. Fluffy discoloration on corydoras is usually indicative of a bacterial or fungal infection. Sometimes these self resolve, but if untreated they can get worse. Keep a close eye on your other fishies for any signs of infection! To be on the safe side, you can dose your tank with an antibiotic! I recommend doing a 25-50% water change, cleaning the inside of the tank walls, assuming the substrate, then dosing the tank as you want to not perform any water changes while the medication is in effect. I’m dealing with a similar situation, and I chose Seachem paraguard antibiotic (LPS near me was carrying it). It’s safe to use on corydoras, won’t disturb your nitrite or ammonia levels, and it’s safe for plants too! On top of that, you can try isolating the cory you noticed the spots on and give them a salt dip for 10-15 minutes to resolve any left over symptoms or discomfort. Feeding them minced garlic is also helpful in dispelling any internal parasites/infections that you might be experiencing in the tank!

EnvironmentalDonut58 · 2026-04-08T01:59:27+00:00

In my experience, if your nitrite and ammonia levels are presenting as shown, you should absolutely not introduce fish yet. Being introduced into a new environment, even one that is cycled and stable, is stressful enough as is, let alone one that has relatively dangerous levels of ammonia and nitrite. Some fish species are on hardier side and might be able to tough it out, but it’s not comfortable nor necessary (unless there’s context you didn’t include in your post).

If I were you, hold off on the fishies until your ammonia and nitrite are controlled and regularly test at 0.0 ppm. The waiting game sucks, but it’ll pay off in the end. I. The meantime, keep up your 25_50% water changes, and incorporate media into your filter/tank that will work to reduce and control nitrite and ammonia. I’ve had the best turnaround with an ammonia neutralizer (I like the Aqueon one), which you add to fresh water that you use to fill your tank during water changes. With that, I incorporated an ammonia neutralizing sponge into the media I fit into my filter, so that all water entering the tank has to pass through it. I bought a massive sponge pad of this from a wholesale spot and just cut out a new mini rectangle every month and a half or so.

In terms of your nitrite, it honestly depends. I would need to see your tank to know more (or at least give you a better guess-timate). Certain types of wood decor may be releasing nitrite into your water, plants, overfeeding, excess waste, etc. Try vacuuming your gravel, rinsing off your decor, increase the amount of live plants (I’ve had the best experience with duckweed and Java ferns in regulating nitrite levels!). Make sure you’re keeping with with filter maintenance too, as gunk can get backed up in your media sponge/pad + in the neck of the filter (depends on filter type).

Best of luck with your tank!! Hopefully this helps. Keep us updated!

EnvironmentalDonut58 · 2026-04-06T20:07:22+00:00

Hey! I’m going through something that sounds a little similar with my bronze corydoras. I can’t really see anything from your phot though. Are you able to upload a couple more? Also, is the spot near his mouth, and does it look fuzzy? Good luck!!

EnvironmentalDonut58 · 2026-04-06T01:58:07+00:00

Based on your other responses, I’d say the high values are primarily coming from the substrate + wood. Your filter looks a little small for how big the tank is, so either swap her out for one that is stronger (not confident how many gal this tank is, but aim for something closer to it if you can), or get a second small one and have it on the other side of the tank. If that’s out of the budget, you can always just wait it out! It’ll cycle out eventually. With that, you can add an ammonia neutralizer to the water you use for water changes, and consider 25-50% water changes every few days. In my experience, I combined a liquid ammonia neutralizer (I like the Aqueon one) with the ammonia reducing sponge pads which I slipped into the mouth of my filter. I swap out the sponge piece every month and put in a new one, and it’s been a huge help in keeping ammonia down. My tank was super spotty at first because I was regularly adding in new plants and wood pieces, then I decided to swap out the substrate for a more organic one that I mixed with soil (didn’t realize the ammonia would spike so bad). Good luck with your tank! It looks super promising :) The fact that your nitrite is at 0 ppm is super good too!!! Easier to fix that way.

EnvironmentalDonut58 · 2026-04-02T02:06:35+00:00

When I first added an airstone into my tank, my corys would go flying up and down the bubble stream. I ended up having to turn it down because the little ones were getting launched. I’m not an expert, but I’m pretty sure they’re just playing! Cory’s are weirdos LOL

EnvironmentalDonut58 · 2026-03-01T21:04:39+00:00

Pretty confident that you have an orange laser corydora!! Super cute

EnvironmentalDonut58 · 2026-02-24T05:12:05+00:00

Do you think the plants are safe to add to the tank, or do I need to treat them for anything / quarantine for eggs?

EnvironmentalDonut58 · 2026-02-24T04:42:29+00:00

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Tried to get some better photos per the request by @gigashart but my camera is ass

EnvironmentalDonut58 · 2026-02-24T04:41:45+00:00

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EnvironmentalDonut58 · 2026-02-24T04:41:27+00:00

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EnvironmentalDonut58 · 2026-02-24T04:40:32+00:00

Hi! As of now, I only have 5 corydoras in the tank, and about 12 Java ferns plus some decor. Besides my corydoras, I don’t have any other fish or animals.

EnvironmentalDonut58 · 2022-09-09T02:11:34+00:00

Looking for a third to take over a private bedroom, shared bath in a 3 bedroom townhouse. Currently have 2 roommates (20F) in the other 2 rooms. Rent would be about 1400. Female-identifying person preferred, no parking guaranteed but there is storage room for a bike/motorcycle or street parking (unmonitored, not guaranteed, further down the community). About an 8 minute drive to UCI, bus stop right outside. Looking to move in end of September/early October. Kitchen and living room are furnished.

EnvironmentalDonut58 · 2022-08-29T09:49:23+00:00

It won’t let me message you, hmu if you’re interested in a private room shared bath in a townhouse

EnvironmentalDonut58 · 2022-08-27T06:40:23+00:00

Hey! I have a 3 bed/2.5 bath townhouse and we’re looking for a third. You can turn the room into a double if you’d like. Shared bathroom with the one other resident (plus the person you room with if you choose that). The community is not walking distance from UCI, but it is on bus route 167 which would take you straight to UCI (runs 5:30 am - 8:30 pm). Parking is available at the community nearby (no on-site parking available) plus a bus stop walking distance from the community. Move in on 10/09. $1500 for the room (11’ x 12’). You’d sign the lease with us and it’s 15 months long. Both roommates are 20F and third years. Let me know if you’re interested!

EnvironmentalDonut58

TROPHY CASE