In Self-Realization Fellowship, two of its gurus say that mermaids exist, at least in heaven. And since this is said in the guru Yogananda's Autobiography of a Yogi, and claimed to be from a freshly resurrected wisdom-avatar that is revered as Sri Yukteswar, I suppose few or none in SRF will gainsaiy it.

Then, according to Yogananda, his departed guru communicated one day:

"The ordinary astral universe . . . is peopled with . . . myriads of fairies, mermaids, fishes . . . goblins, gnomes, demigods and spirits." - Autobiography of a Yogi [13th edition, page 355].

It is a passage from chapter 43, "The Resurrection of Sri Yukteswar", and is also in the first edition, which is online.

"The astral universe" may be translated as 'heaven'. In our times, faith in heavenly mermaids (and gnomes , fishes, etc.) is not backed up as much as in earlier times.

Blind rejection and blind acceptance of the myriads of mermaids in heaven are both blind - which may be understood as sort of defective as compared to being seeing, or what? So how to deal with that part of the SRF (mind) universe?