Wouldn't recommend setting a stop loss on Bitfinex.

a) U are just asking for it to get farmed against the grain of the market by exchange insiders and/or bots simply farming by guessing (my bet is on exchange insiders).

b) If it triggers, u are likely to find that most of your trade actually gets triggered at much higher rate than the Stop Loss that u set.

Trade with a mental stop loss where u decide that if the price breaks above a certain value, then plan to leave your position on next correction/spike depending on which way u are trading.