The heat is on, and that can mean warmer waters too.
The DNR saying because of that, people may see more dead fish, called 'fish kills'.
"Fish kills in the wild are often due to a multitude of reasons. Often multiple reasons at once," said Nicole Nietlisbach, an aquatic veterinarian for the Wisconsin DNR.
One of those reasons is hotter air heating up the water.
"It's part of the natural world and the natural environment," said Nietlisbach. "It's good to kind of remind the public that this can happen and remind them what to do when and if they do see a fish (sick)."
Those reasons also include pathogens that thrive in warm waters and what could be a low level of oxygen as well.
Algae blooms can absorb that oxygen which fish need to live.
"The algae is actually utilizing the dissolved oxygen within that water causing a low oxygen state to happen," said Heather Schlesser, an agriculture educator with UW-Extension Marathon County.
Those algae blooms can also block other underwater vegetation from growing and giving off that oxygen.
"(Algae) will actually take up that oxygen," said Schlesser. "So then if there's a lot of them, they also block out the sunlight and everything so that prevents the plants from growing underneath and the plants of course help put oxygen back into the water."
The DNR suggests to look out for fish swimming abnormally, gasping at the surface, and any physical flaws such as bumps or white spots.
For those who accidentally catch a sick fish, the DNR suggests to wear gloves when handling it and call your local fish biologist.
"The local biologist can check it out if they're available," said Nietlisbach. "We can collect the fish from them and we can look into what's going on with the fish."
These sick fish should not be consumed by any person or pets.
The DNR says they want to be let known of these so they can make sure that there's not a bigger issue going on.
