I have noticed more parasites in early spring then anyother time of year. I wounder if it has somthing to do with there imune system being more stressed after winter? You could keep a bucket of saltwater next to you while fishing and give them saltwater dips to kill the parasites. Dont think it would be very productive.
Yes fish are more stressed coming out of winter, and the spawning period, which is in the spring for the sunfish family is stressful. If the water is still cool or there are major swings in water temps (common in early spring) they are compromised a little in immune response and are stressed.
A salt dip is very effective on EXTERNAL parasites if done correctly, but obviously only on those fish that are dipped. For very weakened fish a salt bath would be a better choice as a salt dip for them could kill them.
If you want to read all about salt treatments of fish here is an article written by a Dr. Myron Kebus that is a well know fish pathologist in Wisconsin. I know he's referring to Koi but the same principal applies to other species although species do vary on their sensitivity to salt treatments.
http://www.aquarticles.com/articles/ponds/Kebus_Salt_Treatments.html When I dip I remove the fish and put it back in the original water after it goes on it's side. Refer to the article for the amount to add to water.
If I had a parasite problem in any of my ponds I'd take five gallon bucket mixed to a 3 percent saltwater solution and do some fishing. Before releasing I'd dip the fish in the solution and as soon as it goes on it's side I throw it back into the pond.
