Partially paralyzed fish?

[Neontetra33]

I've kept fish for 23 years and grew up with my parents having fish but I've never seen this before. One of my harlequin rasbora suddenly, over night with no warning, started swimming erratically and in circles, upsidedown. It's lost a lot of colour and seems to have a cut on its dorsal fin and some paralysis?

I thought swim bladder issue? And perhaps a parasite latched onto dorsal fin while it was resting on the bottom? It swims crazily for a few minutes then settles on the bottom for a rest. Idk, it just came on over night.

Anyone know what this could be? I doubt there's a way to help this particular fish, but I don't want it spreading to my other fish if it's catching.

My tank is 110 litres and, if anything, understocked. Checked water levels, all good, temperature fine. This fish is almost 2 years old, maybe even over 2, I lose count. All others healthy.

It's clean up day today and the rest of the tank is clean but, typically, he chose to rest where the shrimp feed so it makes my tank look messy

Thanks for the help!

 

[GaryE]

A lot of things appear randomly in fish, as they do in us. A fish can have an internal growth, an injury or a disease that causes paralysis. It can be neurological, or not. The one thing that I have seen to be in common when this happens is the fish dies. I wish I could be more positive.

 

[Neontetra33]

A lot of things appear randomly in fish, as they do in us. A fish can have an internal growth, an injury or a disease that causes paralysis. It can be neurological, or not. The one thing that I have seen to be in common when this happens is the fish dies. I wish I could be more positive.

Yes, I am fully suspecting it not to recover, I'm just concerned it might spread to the other fish, whatever it is. Hopefully it will not I've had fish randomly die before but they don't usually have this much energy beforehand

 

[GaryE]

When I have seen this, I have never seen it spread. The only thing that would is fish tb, and that would happen of the fish died in the tank and was scavenged. But that is not a likely cause.

 

[Colin_T]

Euthanise the fish because it won't recover.

This problem is normally an infection in the brain, a stroke, or a head injury (infection being the most common). If it's caused by a protozoan, bacterial or viral infection in the brain it can spread, and it's usually caused by a dirty tank and filter. Cleaning the tank usually prevents it spreading and adding salt (2 heaped tablespoons of salt per 20 litre/ 5 gallons of water for 2 weeks) can also help stop it spread if it's caused by one of these infections.

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To reduce the chance of fish getting sick when a fish dies, or if a fish gets sick, do the following.

Remove the body asap so nothing eats it. A lot of diseases are spread this way.

Test the water for ammonia, nitrite, nitrate and pH.

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate every day for a week. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.