Trap saber salmons in a fish basket, then cryo the fish. Keep them cryoed until you want to tame a shadow, then make another fish basket, release them from the cryo and trap them again. Put the fish basket in your hot bar and submerge yourself to reset their timer. No wasting fish baskets. Get lots of fungal wood to make more baskets as they will destroy after you "tame". Also don't punch them because they tell their friends and fck you up
I always kill these fish when they grow huge. Idk why, it just makes me feel like defeating an alpha (Which I never have), and also for the prime fish meat. Not much to say here but... They have a bleed effect, and they all swarm you like megapirahnas when one is attacked. If no other sabertooth salmons are there, it will flee (According to dossier I think).