I've desynthed the fish - leveled up from 0 to 83.72 so far - managed to do that in 277 desynths.

Out of 277 desynths I got:
- 195 fine sands
- 32 fine sands HQ

- 1x clear demimateria II
- 1 grade 3 clear prism
- 1x yellow pigment
- 8 green pigment
- 8 red pigment
- 2x blue pigment
- 9x grey pigment
- 1x brow pigment
- 2x grade 5 dark matter
- 1x clear demimateria III (desynth 80+)

Used all big fish for desynth - of course higher ilvl gives higher desynth gains - ilvl80 fish give ~0.3-0.4 per desynth for 50% chance.