Nodules on Cory and other Corys recovering from something unknown

[BrendanL]

Several weeks ago I introduced some new driftwood from the beach to my 180L tank. I had thought suitable preparation of the wood took place and there were no issues for a few weeks.

More recently, I changed my pebbles to Aqua One black silica sand (a fine gravel). I did this in stages, didn’t change any other water/filter material etc and have even retained some of the old pebbles in some breathable nylon bags underneath the silica. There didn’t appear to be any ‘new tank’ issues as a result of this activity. I am running a UV Filter as well. The Cory’s and the bristle nose appeared OK with the new base, but yes, they were both on my mind during planning and transition.

A few days ago the bristlenose died, with no external signs. TBH, there were no internal signs of gravel – I just needed to check.

Then one of my smaller Cory’s went quiet and developed some reddening under a fin. I isolated him initially in a floating breeder. Then a larger Cory began going quiet. I moved all Cory’s (two larger, three smaller) to a separate tank. Shortly after, the large bronze just died – he wasn’t the same one that initially went quiet. No external signs (I didn’t open him up this time).

While the pebble to gravel transition was the most recent and could seem as a potential issue, it was too much of a coincidence for me that they would all go downhill so fast?

My second thought was on the driftwood. Was it still leaching out salt? There have been no issues with ‘regular’ fish in the main tank - just the Corys and the bristelnose. I’ve done a number of partial water changes in both the main and isolated tank over the last couple of days to hopefully dilute any salt if that was the issue. I have also removed the driftwood.

The Corys in the isolated tank do seem to be more active now, so perhaps the water changes and reducing any possible salt is bringing them back to health?? Time may need to tell on this.

However, on the larger Cory, these nodules are present. I have not seen them before. Are the nodules parasitic or cysts? And what can I do about them?
Also, his eyes are possibly of concern too? No other fish seem to have this

 

[Byron]

I will alert @Colin_T and @DoubleDutch and @GaryE who may have an idea. I've never seen anything like this.

 

[JuiceBox52]

If the fish should die, which I hope it doesn’t, send it to a lab for testing. This is indeed strange and very concerning

 

[GaryE]

That is bizarre. I have never seen it before either. I hope I never see it again.

In my book of fish photos I'd rather not see, The Manual of Fish Health by Andrews, Exell and Carrrington, it lists a very similar looking problem under nodular diseases, and says it is caused by "various microsporidian and myxosporidian parasites" There is fish to fish transmission, but the sources are unknown. There are no treatments.
It would seem there are quite a few candidates for what is doing this - a lot of parasites.

Do you think it may have hitched in on the driftwood? The odds are small, but these things happen.

 

[Rocky998]

Wow... That is so weird... Never even thought there could be something like that for fish.

 

[BrendanL]

Thanks for the info today guys. The potential rareness is interesting.
I've just started a course of Melafix. I'm not sure how much it will help with whatever those things are, but may help with the pop-eye.
Will update as things progress.

 

[DoubleDutch]

That is bizarre. I have never seen it before either. I hope I never see it again.

In my book of fish photos I'd rather not see, The Manual of Fish Health by Andrews, Exell and Carrrington, it lists a very similar looking problem under nodular diseases, and says it is caused by "various microsporidian and myxosporidian parasites" There is fish to fish transmission, but the sources are unknown. There are no treatments.
It would seem there are quite a few candidates for what is doing this - a lot of parasites.

Do you think it may have hitched in on the driftwood? The odds are small, but these things happen.

Quite interesting Gary. Can't find any pics though with these kind of stuff on the body.
Somehow there is a buildup of pressure inside the body. The eyes bulge (the weakest spot of the fish).

What are the fish fed exactly. Have seen these signs mainly in Sterbai eating beefheart which they aren't able to digest properly.

 

[GaryE]

The pics I found weren't on Corys, but presented close to this. It looks like a gas buildup in the fish.

 

[DoubleDutch]

The pics I found weren't on Corys, but presented close to this. It looks like a gas buildup in the fish.

I think it is fluid.

This Cory seems to be on the old substrate ?

 

[Colin_T]

It's not microsporidian

the driftwood is unlikely to be the cause

it could be gas bubble disease, bacteria or alkalosis (sudden change in pH).

 

[BrendanL]

The pictures above are from the hospital tank - with different substrate. Feeding is generally flake and spirulina discs. There had recently been some bloodworm and cucumber.
Two of the younger corys are back in the main tank now with no issues and feeding well.

The larger one with the bubble remains isolated with one other young cory that's still looking weak and has some occasional erratic swimming.
The bubble hasn't really changed. A couple of days ago the fish was tending to float up a bit towards the tail, but that has stopped & he's back on the ground fine. There may have been some dropsy/whiter/scaling sticking out like boating towards the tail end too & I did think I may need to call time, but that also seems to have settled - or certainly hasn't gotten any worse (photo from yesterday attached)

Will keep up the Melafix.

Thanks @Colin_T . Good to know about the driftwood. And others, re gas too. I can't account for any sudden pH changes, besides a final top-up of the new silica sand leading up to it, but that had been rinsed several times in fresh, filtered/non-chlorinated water.

 

[Colin_T]

The fish has pop-eye (the eyes are bulging out) and this can be from gasses being pushed out of the body or a bacterial infection in the head. If the fish has stopped eating, I would euthanise it. If the fish is still eating well and the bubbles start to go away, then monitor and see how it goes over the next few days.

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The white stuff on the fish is excess mucous produced by the fish to help reduce irritants affecting the fish. Fish naturally have a thin clear film of mucous over their body & fins to help them slip through the water and to act as a first line of defense against microscopic disease organisms. When fish are stressed or exposed to chemicals or disease organisms, they produce more mucous and it appears as a cream or white film over part or all of the body.

If the excess mucous is only over a small section of the fish, it is usually caused by a wound or external protozoan infection.

If the excess mucous is all over the body, including head and fins, it is caused by something in the water (chemicals, medication, etc).

The Corydoras catfish in the picture has excess mucous all over the body so make sure the water quality (ammonia, nitrite, nitrate & pH) are good, and make sure you don't overdose with chemicals.

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To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.

When you measure the height, measure from the top of the substrate to the top of the water level.

If you have big rocks or driftwood in the tank, remove these before measuring the height of the water level so you get a more accurate water volume.

You can use a permanent marker to draw a line on the tank at the water level and put down how many litres are in the tank at that level.

There is a calculator/ converter in the "FishForum.net Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.

Remove carbon from the filter before treating with chemicals or it will adsorb the medication and stop it working. You do not need to remove the carbon if you use salt.