I think that the term Halibut refers to the intended consuming fish.
Most bait companies use commercial pellets from fish feed producers, buy them in bulk and sell them at quite a profit in smaller packages, often with a different name. The old 'elips' referred to the eliptical shape (these tend to fall through the water slower than cylindrical shaped), theoretically giving less wastage.
Salmon, trout pellets contain substances that impart a pink tinge to the flesh similar to the compounds found in shrimp and krill for example. The reason for this is that commercially (aka cage, farmed etc) grown/reared fish would have pale/greyish flesh rather than pink associated with that species.
Things have changed over the years regarding formulation and acceptable additives, oil content and shape.
Formulation of high oil trout/salmon pellet from yesteryear......(very successful barbel bait, possibly the best IMO and supplied by Bfw)
Oil 33%
Protein 38%
Fibre 1%
Ash 7%
Vitamin A 10000 iu/kg
Vitamin D 1500 iu/kg
Vitamin E 250 iu/kg
Contains: Fishmeal, fish oil, wheat, soya, maize gluten, wheat gluten, Vitamins and minerals
Copper Sulphate
Ethoxyquin (antioxidant)
Astaxanthin (pigment)
Canthaxnthin pigment)