Aquariums: Is this that fungal parasite?

Yeah, unfortunately that looks like Cladogonium or Clado for short. You can find everything you ever wanted to know about Clado, including various treatment methods from this youtube video [here](https://www.youtube.com/watch?v=rLuULEsJcBY). From a TL;DR standpoint, its a type of parasitic algae. Its a secondary infection to an already stressed shrimp. Its not always deadly, but it can spread similar to typical algae in a tank, in this case shrimp will walk over spores and get infected. As its an algae the best methods of combating it are hydrogen peroxide for the whole tank, and salt dips for the shrimp.

This shrimp in your image is pretty along in its infection, and while you can treat for it with salt, I personally never had success with an infected shrimp at this stage even with dips, you are better off keeping it in quarantine and just treating the whole tank. How I’ve treated my tanks in the past when shrimp had clado was I hit the tank with 1.5ml per gallon of peroxide 2-3 times over the span of a week (similar to general algae treatments). So treat day 1, for day 2 skip, then treat again day 3, day 4 skip then treat again day 5. I’d mix the peroxide in a small cup with tank water, then pour the mix all throughout the tank with the filters turned off for ~60 minutes. Also bonus steps are to feed your shrimp colony reinforced foods. However if its only one shrimp infected, typically a peroxide treatment is enough for the tank, though since clado is slow moving, it may reappear months later depending on various factors.

> Ps. When you buy new fish or shrimp, do you normally quarantine first?

I typically don’t but you can avoid all this if you buy from breeders who do not import, but sell tank bred shrimp only. Imports that were bred outdoors typically introduce things like clado to a tank. It should be on the seller to quarantine prior to resale.