Bonefish easily.
People are having WAAAAY too much trouble with something that is exceedingly easy to do.
It needs to be done on a toxic planet.
It needs to be done at localized night, the day/night cycle of most planets is around 10 minutes each.
You need to be on top of a depth of AT LEAST 50 units, the fish won’t easily spawn in shallow waters.
Use the shadow lure, if you’re fishing the game gave you ALL LURE RECIPES, you need ANTIMATTER, METAL PLATING and CYTO-PHOSHATE to make some, the latter can be mined from plants in deep water planets, including toxic ones.
The second rendezvous has a toxic planet that meets all of these conditions, I’ve spent 30 shadow lure on one night cycle and managed to get 11 of them, if you’re having trouble, are on a toxic planet at night and using the lure, dive underwater and check the depth, it needs to exceed 50 units of depth down.