Today I caught two trout that were both showing signs of fungus and the fight was poorer than expected. I've seen a few fish in this water with white patches and it does seems that some fisheries are more affected than others.
I wasn't sure whether to put them back or kill them, and in the end I put them back, thinking that they were obviously feeding as they took my emerger pattern.
1. Should I kill fish that show signs of fungus? 2. Will the fish get worse or can it recover? 3. What causes the fungus?
The fungus name escapes memory at the moment, seems to affect mainly Rainbows in warmer weather. Once the fungus gets going the fish will swim oddly (often on one side), go blind so swim around in circles and then die. I think most fisheries would prefer that you removed the fish.
Again the dear old European Union is to blame, I know we should not always blame them but on this occasion it is the case, as they have banned fisheries using the only effective treatment. Sensible fisheries will screen out any obviously sick fish and once the water temperature drops it will go on holiday until next summer.
'Those are my principles. If you don't like them, I have others.' - Groucho Marx.
I may be wrong, but it doesn't seem like whirling disease. The sites I looked at don't mention fungus, just the whirling and body deformation.
I've noticed that there seems to be one or two particular fish that are worst affected. you can spot them from the white patches. However, they've been there since at least september and they don't whirl, they just seem maybe slightly lethargic, although I have no way to compare them to the healthy trout. I presume they must be feeding to have survived until now, and I'm sure they are the same fish.
Sounds like UDN (ulcerative dermal necrosis), but as far as I'm aware, this only affects salmon and sea trout. I would inform your local fisheries officer of this matter as soon as possible and get it clarified as these fungal type of diseases are generally contagious. Best, Gnat.
I always put these sort of fish back as I am sure the pike appreciat an easy meal. The last time I saw one was at Haningfield, it was a huge fish of around 8lb and was covered in fungus from head to toe. Peter
Whilst I am certainly not an expert in this area, I think Dunc45 may be correct in that it is saprolegnia - this is a common fungal growth and one which can take a severe hold on salmon and trout either in the spring and back end (season's that is, not part of the salmon ;D) It is quite common to spot many fish like this close to spawning time when they have suffered lesions, abrasions etc and the fungal infection has taken hold.
Whilst Bruce makes a fair point about the use of malachite green in fish farms, it is fair to say that its ban has had a devastating effect for those wild fish hatcheries who are attempting to recondition spring salmon kelts in an attempt to avoid continuing having to take fish each year from the wild. Malachite is very effective treatment for saprolegnia, other treatments, like salt baths are not nearly as effective. It is just unfortunate that again the wild fish have been subjected to another 'side effect' of the fish farming industry.