Bronze Cory Flashing and Twitching

Tank
What is the water volume of the tank?
30G
How long has the tank been running?
1y
Does it have a filter?
Yes, two 20G filters and a sponge
Does it have a heater?
Yes
What is the water temperature?
78F
What is the entire stocking of this tank? (Please list all fish and inverts.)
4 Adult Bronze Corys (3 Albino, 1 Bronze); 5 Youth Bronze Corys (<1inch); 1 Mystery Snail; 7 Young Guppies (Unwanted but can't catch without destroying the plants... for now)

Maintenance
How often do you change the water?
Once a week
How much of the water do you change?
15-20%
What do you use to treat your water?
Seachem Prime, Seachem Neutral Regulator
Do you vacuum the substrate or just the water?
Vacuum substrate

*Parameters - Very Important
Did you cycle your tank before adding fish?
Yes
What do you use to test the water?
API Freshwater Master Kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 0-5.0ppm
pH: 8.4+ (This is high for them I know, but the tapwater here is 8.6+ and they've been living at this level for a year with no other issues)

Feeding
How often do you feed your fish?
Once a day/twice a day split up
How much do you feed your fish?
A few pellets everyday, some lose food, I usually watch to make sure everyone eats (the tank is right by my desk, so I can tell when they need food or when they are just being corys)
What brand of food do you feed your fish?
Hikari (blood worms, tubifex, daphnia)
OmegaOne Shrimp Pellets
Do you feed frozen or freeze-dried foods?
Freeze-dried

Illness & Symptoms
How long have you had this fish?
2y
How long ago did you first notice these symptoms?
1w
In a few words, can you explain the symptoms?
Flashing when swimming, cramping (only one fish does this?), slightly red on some of the albinos
Have you started any treatment for the illness?
No, changed water and cleaned substrate to make sure it wasn't water params, still occuring
Was your fish physically ill or injured upon purchase?
No, bronze cory lost his eyes due to an early bacterial infection (2+ years ago)
How has its behavior and appearance changed, if at all?
No behavior changes beyond flashing and twitching, still eat fine and are very active.

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)
So a week ago I got some new cory babies and I added them to my tank. (I would quarantine but I'm only allowed one tank in my apartment) No issues besides one dying from stress. The week before that, I added some smooth(ish?) gravel to the left side of the tank, and no issues came up. This week, I notice one of the albinos flashing, which isn't super abnormal, because they often try to filter through small snails, but they kept doing it, and soon I saw the other adults do it as well. None of the babies were doing this, whether they were new or already part of the tank. The blind bronze cory didn't do it as much, but I still saw them do it. None of the fish are bloated (the bronze has always been weirdly thick compared to the albinos) and all are eating normally. The guppies are sometimes flashing, but happened before due to fighting. Yesterday and today I have seem some of the baby cories flash the same way as the adults. All fish are eating normally, and sides the flashing they still seem unaffected. One albino will sometimes twitch like he is being poked, but none of the others do this. None of the cory cats' barbells are showing fungus or fuzzyness. I am colorblind so I cant really tell if their gills are red, but I haven't seen any spots that look like ich. Below are photos of the adults, the spots on them is sand not ich! It came off right after the pictures! Possibly related but unsure, sometimes the blind bronze cory will "break out" and I will wake up to large white spots on their tail fin. Way to large to be ich, and almost look like one of the other corys laid eggs on him. He never shows irritation and after they rub off there is no lasting effects.

I was thinking that the gravel I put in might have been too sharp for them, and I'm going to remove it, but I don't want to assume that's the only issue thats going on here.

 

The symptoms point to potentially some type of flukes, my Cories displayed similar symptoms when they had gill flukes. It's also possible when you added the gravel, some particles came off it that irritate the cories when it gets in their gills. But that's just speculation honestly.

If it is flukes, it can be treated with PraziPro or any other Praziquantel containing products. It's safe for inverts and plants so you don't have to worry about that. Unfortunately there isn't really a way to confirm a diagnosis of flukes without taking a scraping from the scales or a gill clipping and looking at it under the microscope. Yeah... No one is going to do that to their cories.

 

The symptoms point to potentially some type of flukes, my Cories displayed similar symptoms when they had gill flukes. It's also possible when you added the gravel, some particles came off it that irritate the cories when it gets in their gills. But that's just speculation honestly.

If it is flukes, it can be treated with PraziPro or any other Praziquantel containing products. It's safe for inverts and plants so you don't have to worry about that. Unfortunately there isn't really a way to confirm a diagnosis of flukes without taking a scraping from the scales or a gill clipping and looking at it under the microscope. Yeah... No one is going to do that to their cories.

Thanks! I know that adding meds when they aren't needed can sometimes cause more issues, so after i remove the gravel do you think it would be smart to wait a while to see if the issues stop? I've never really had experience with flukes, so I'm not sure how urgent this is for them?

 

Thanks! I know that adding meds when they aren't needed can sometimes cause more issues, so after i remove the gravel do you think it would be smart to wait a while to see if the issues stop? I've never really had experience with flukes, so I'm not sure how urgent this is for them?

Yes, see if removing the gravel will help. Flukes aren't a serious condition, they're pretty much fish fleas. They can eventually damage the gills if they're gill flukes though, so they do need treated.

 

Do you notice if the flashing occurs after waterchanges or feeding. How do you treat the water ?
BTW ; "No issues only one died of stress" sounds weird to me. Fish don't "simply" die of stress.

 

Do you notice if the flashing occurs after waterchanges or feeding. How do you treat the water ?
BTW ; "No issues only one died of stress" sounds weird to me. Fish don't "simply" die of stress.

Sorry for getting back to this so late! I took all the stones out and they doing much better! The one that died just refused to eat, which seemed to be because he was so stressed.