In the world of my story, merfolk have been captured by humans to serve the cruel purpose of providing their colorful scales to make jewelry, chandeliers, etc, with their colorful scales. I'm not looking in this post specifically for how this would work biologically - I've mostly worked out though that it is not an extremely gory process - ie, the merfolk are not skinned alive and then left for dead. The scales come off with a sharp knife, and will regrow some months later.
More of what I'm interested in is getting feedback on the system that would need this to work. I'm in an early 19th century setting circa 1800 - 1850. I've figured so far that this is what I would need.
-for a group of around 30 captive mers, a cove near the ocean has had it's exit blocked off to hold the mers in. The mers require the water to be changed periodically, so there are channels controlled by sluices that let water in and out. Food is provided by dumping a porridge-like mixture into the water.
When a mer is ready to be scaled, they are lured over by the release of food, and then caught around the neck with a staff with a noose around the end. They are then pulled into a cage in the corner of the pool, where they are winched up, then bound. Any mers that attempt to stop this, or misbehave in general, are struck with long staffs. This is not always needed however, as even with the water being changed out periodically, it's lack of natural movement has resulted in a numbing effect on the minds of the mers. They can function but it is much more difficult.
The mer to be scaled is then brought to a person sized bowl, where they are secured at the wrists and around the end of the tail just above the fins. The mer is provided with a wooden dowel to bite down on (not out of kindness - it helps them stay more steady) and then the scaling begins.
A well practiced scaler can remove the scales with minimal blood, though some is always to be expected. Extra care is taken around the tips of the fins and the "folds" in the front and back that are not very visible, but have smaller scales than the normal thumbnail sized ones.
Following the scaling, the mer's now bare tail-skin is cleaned off to prevent infection, and then is released back into the pool.
So far as I have figured, my scalefarm at the start is able to be manned by two - the master and and apprentice. As the number of mers increases to thirty, a second apprentice is taken on. The apprentices sleep in a bunkhouse adjoining the master's quarters and office.
The farm itself has a pontoon bridge going around the whole edge of the pool to aid in watching the mers. the front of the farm and the seawall are blocked off by netted fences higher than a person.
Lastly, the farm has a small forge for maintaining tools and fixing mechanisms in the sluice gates.
So that is my outline of how all this works. Let me know how you think this could be improved, or how it would be ramped up for a larger operation (or downgraded for a smaller one).
This practice is legal, though there are regulations on it. This is in the broader context of the human nation and fractured merfolk city states being at war with each other for the past 80 years or so. As the only exposure most humans have to merfolk is seeing them sedated in farms or attacking human shipping, they are viewed mostly with contempt.