Critter latched onto fish

[accidental_reefer]

Hello, so I haven’t added anything to my tank in about a year, except in the last month (1) I supplemented my tank with liverock and I added some (2) macro algae, (3) frags, and (4) a quarantined tailspot Blenny, which is now dead.

Saturday I saw this critter on my tailspot. The critter went MIA the next day, leaving some damage / white markings on the part of the body it was covering. The Blenny looked active and robust yesterday but this morning I found the Blenny dead.

Any idea what this critter is? I assume I should find and destroy?

 

[Crabs McJones]

Parasitic isopod, known as cirolanid isopod
catch the fish and do a freshwater dip if possible

 

[BristleWormHater]

Cirolanid for sure, did you remove it?