This medium is selective for growth at pH 9 and Vibrio spp. are not the only bacteria that can grow at that alkaline pH. The tracks may be the result of insects or mites tracking contaminating bacteria such as Bacillus spp..

Agree with Dr Phil Geis. Mites might have contaminated the media and while moving on media they might have taken some bacteria along with them and spread them throughout the media which resulted in such "branching type colonies"

Hi,

You need some biochemical test. I think this Vibrio.

It is mite contamination, I have found them on my plates too. You can see them with stereo microscope.

its contamination