How wider should I open from CO when there's a fish(we don't know what type of fish he is)or nit in the blinds? The other 2 players are regs who aren't 3betting very often in order to force us to tighten our range. In grinder's manual which was written in 2016, he says to go for a 37.5% range (3x sizing for fish and 2.5x for nit) instead of the defeault 25% range(2.5x sizing). The book is a bit old though and so I want to see if this strategy of opening that wide is correct for micro stakes today.

Also if fish or nit is in the SB instead of BB, does this mean that our range needs to be tighter than this 37.5% range? I think if fish or nit is in the SB, this means that they won't enter the pot as frequently as if they were in the BB(for nit that's for sure. I don't know though if the fish will play tighter from SB than BB in this spot). Peter doesn't talk about this specific scenario though and so I guess there won't be any significant difference. What's your opinion?