Bacterial, Parasite,or Fungus?

Tank

I have a 20 gal talk that’s been running for about 8 months and was fully cycled beforehand. It has a filter and heater set to about 78f. There are 8 harlequin rasboras and 9 silvertip tetras.


Maintenance

I typically do 30% water changes once a week, vacuuming mostly the substrate, then treating the new water with Prime.


*Parameters - Very Important

I always test the water with the API Master Test Kit.


Ammonia: 0

Nitrite: 0

Nitrate: 10ppm

pH: 8.0


Feeding

I feed the fish once a day with TetraMin Tropical Flakes, and occasionally freeze dried brine shrimp. It’s hard to say exactly how much I feed but I usually try feed a few good crushed pinches of flakes (2-3). The little guys are like piranhas.


Illness & Symptoms

I have had the group of rasboras ever since I could put fish in the tank, about 7 months ago after it was cycled, and never had any problems with them. The silvertips were added about 4 months ago and I hadn’t had any problems with them either. All fish were bought from reputable small sellers since I refuse to buy animals from Petco/PetSmart anymore.


I didn’t notice anything going on until yesterday I had to put down one of my rasboras since I noticed during feeding it had a completely sunken belly and had trouble swimming with the others (it also kept shifting nose-up). Today, I noticed 2 other rasboras had what looked like small white fuzzy spots on both their eyes, one was worse than the other but they were still eating and behaving normally. I went ahead and treated the whole tank today with API General Cure since I didn’t know what specifically was in the tank infecting the fish. I know it is either bacterial or internal parasites, but I haven’t seen any weird poop so I wasn’t sure. The white eye fuzz had me thinking fungal but the rasbora that died didn’t have it which is why I’m a bit confused on how to go about treating the tank.


As a side note, I have no idea how long the white fuzz has been there since it’s not really something I noticed until actually looking closely at each fish. The silvertips are completely unaffected.


Thank you guys for any help and input

 

It sounds like you are doing a real good job maintaining your tank. From the description reported, the Rasboras might be suffering from a bacterial infection. The fuzzy stuff on the eyes migbt be fungus attached to dead tissue, caused by bacteria. With tiny fish such as Rasporas, treatment with antibiotics probably won't help. IMO, best just to remove any fish exhibiting symptoms asap, as to avoid spreading the disease. Bacterial infections can occur even in clean well maintained tanks.

 

It sounds like you are doing a real good job maintaining your tank. From the description reported, the Rasboras might be suffering from a bacterial infection. The fuzzy stuff on the eyes migbt be fungus attached to dead tissue, caused by bacteria. With tiny fish such as Rasporas, treatment with antibiotics probably won't help. IMO, best just to remove any fish exhibiting symptoms asap, as to avoid spreading the disease. Bacterial infections can occur even in clean well maintained tanks.

I figured it was most likely bacterial. It makes me sad to see them sick since rasboras have been my favorite fish to keep, but I’d rather do what’s best for the rest of the fish. I’ll see how they’re doing in the morning and remove any of the suspected ones. Poor guys

 

What’s your phosphate levels like? If it’s bacteria / fungus, something is helping it and with your low NO3 there is something else up.

 

I don’t have a way to test the phosphate levels at the moment, I’m not sure where to get a kit for that. Would the medication throw off any of the water parameters?

 

I don’t have a way to test the phosphate levels at the moment, I’m not sure where to get a kit for that. Would the medication throw off any of the water parameters?

Not really unless you accidentally kill off the filter. Do you get much algae and other growth? 30% water change is fairly aggressive weekly but won’t help in my case as the tap water is high in PH and NO3 to the point where I have it better managed in the tank. Check your local water report as a starter.

 

You should test the Karbonate Hardness and PH. If your tank is heavily stocked, there could be stress, and when you do a good once a week cleaning, it could cause a PH swing. That is never good if its a large swing or keeps happening. can kill.
As for treating your fish, they don't get "fungal" infections usually, the best thing to do is test the water frequently and maintain stable levels.
Tetras like soft water, these are just my ideas as to what could cause the problem, are any of the fish new from pet store?

 

I do tend to get algae growth, though it usually disappears for a while after a good scrubbing. I’ve always blamed it on the heavy lighting the tank gets during the day.

I do the heavier water changes since the tank is pretty full, but if that’s having a negative impact on the tank I can cut down a bit.

According to my city’s 2018 water report, phosphate levels are 0.063, pH is 7.7 (which is a .3 shift to 8.0 in my tank) and the hardness is 140. Not sure what the unit for hardness is supposed to be since I’m not familiar with measuring those parameters. I’ll have to find a way of measuring the phosphate and hardness levels for my tank.

And no, none of the fish are new but rather several months old.

 

If it helps, here’s a pic of the tank itself and the rasbora with the worst eye fuzz. It’s a bit hard to see, but it’s the best I could get with how active they all are lol.