An Ark dev said that these will be tameable in the future!

Tamable using fish baskets from aberration. They seem to flee from the baskets once placed. It is a good strategy to pen then in with fence foundations and walls, or kite them to a pen. Place your basket on the other side of the wall and catch.

Place a fish basket to tame this.

Trap them in the shallow water so they cannot go anywhere and just place the bucket on the top of them. Bam. Tamed Sabertooth Salmon