Also, please mention the use of puns likening Fish to an aquatic vertebrate has indeed become tiresome.
From the sportsillustrated.cnn.com
The karst geology harbours approximately 7,000 caves and pits, some of which are habitat of the only known aquatic cave vertebrate-the olm.
From the en.wikipedia.org
This scenario would decrease the vertebrate biomass and alter the food web structure in the aquatic system.
From the sciencedaily.com
Among the vertebrate sub-group of chordates the notochord develops into the spine, and in wholly aquatic species this helps the animal to swim by flexing its tail.