Sucking fish and Spiny-finned fish

Sucking fish noun - Marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects.

Spiny-finned fish and sucking fish are semantically related. In some cases you can use "Spiny-finned fish" instead a noun phrase "Sucking fish".

Spiny-finned fish noun - A teleost fish with fins that are supported by sharp inflexible rays.

Sucking fish and spiny-finned fish are semantically related. Sometimes you can replace phrase "Sucking fish" with "Spiny-finned fish", this phrases are similar.