In Regolith Range, I have identified five unique elemental barrels (Jesshums spotted the corrosive one here) that are fairly clustered and do not randomize between map loads (see attached picture: the colored dots correspond to their elements). This makes me think that some combination of their destruction will bring Tannis out upon her fish. There are, what, 120 possible permutations of these five elements that could be the correct sequence? I only tried like a dozen, but will try some more later. If you find the sequence, do post!
Note: the Cryo barrel is up and to the right of the red barrel (the color looks a bit like the icons for the oxygen vents). You can see and hit all the barrels while standing on the little island with the chest and the fishing pole. There is also a randomized barrel in close proximity to the shock one, so you will want to pop that one first to prevent the shock one from inadvertently zapping it and breaking the sequence.