Is this an injury or a disease?

[gwand]

One of my yellow tail Congo tetras (a. caudalis) looks like he was body slammed. See the opaque area on his posterior, dorsal flank and what looks like a pink abrasion on his anterior, ventral flank. Is a combat injury or an infectious disease?

 

[Colin_T]

How quickly did it appear?
Have you added anything new to the tank in the last 2 weeks?
Is there anywhere the fish could have gotten stuck?

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The white bit in the muscle tissue could be a parasitic worm or a microsporidian infection.

The red on the belly looks like a bacterial infection.

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If there's a worm in the muscle tissue you can normally kill it by using Praziquantel or Flubendazole.

Use salt (sodium chloride) to treat a microsporidian infection. Add 2 heaped tablespoons of salt (rock salt, swimming pool salt or plain sodium chloride salt from the kitchen) per 20 litres (5 gallons) of water. Keep the salt in there for 2 weeks.

The bacterial infection might respond to salt (same dose as for microsporidian). If it doesn't improve after 24 hours or gets noticeably worse, then you will need a medication to treat bacterial infections (preferably not an antibiotic).

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Before treating the fish with anything, wipe the inside of the glass down. Then do a 75-90% water change and gravel clean the substrate. Make sure any new water is free of chlorine/ chloramine before it's added to the tank. Clean the filter. Then add salt.

You can deworm the fish in a couple of weeks time if it survives the bacterial infection.

 

[gwand]

How quickly did it appear?
Have you added anything new to the tank in the last 2 weeks?
Is there anywhere the fish could have gotten stuck?

---------------------

The white bit in the muscle tissue could be a parasitic worm or a microsporidian infection.

The red on the belly looks like a bacterial infection.

---------------------

If there's a worm in the muscle tissue you can normally kill it by using Praziquantel or Flubendazole.

Use salt (sodium chloride) to treat a microsporidian infection. Add 2 heaped tablespoons of salt (rock salt, swimming pool salt or plain sodium chloride salt from the kitchen) per 20 litres (5 gallons) of water. Keep the salt in there for 2 weeks.

The bacterial infection might respond to salt (same dose as for microsporidian). If it doesn't improve after 24 hours or gets noticeably worse, then you will need a medication to treat bacterial infections (preferably not an antibiotic).

---------------------

Before treating the fish with anything, wipe the inside of the glass down. Then do a 75-90% water change and gravel clean the substrate. Make sure any new water is free of chlorine/ chloramine before it's added to the tank. Clean the filter. Then add salt.

You can deworm the fish in a couple of weeks time if it survives the bacterial infection.

I just noticed the markings today. There is nothing new in the tank. Thanks for the information.

 

[GaryE]

To me, it's disease. I don't know if it's infectious or if a septicemia type infection hit him for the reasons those things appear, but I wouldn't let the fish die in the tank. Scavenging spreads things that would usually stay contained in one fish.

You have an excellent care routine, so I'd suspect a random infection.