I would fold here.
it is clearly a bet for 12 bux to call 20 bux pot
your AK is not enough to beat his range
his range have set, 4 of a kind, slow played over pair like AA. another AK, some middle pair like 99,TT
if you want to continue the best idea is to X-call turn , X-call river.
but I do think folding is better, because I did not see any fish fold pairs VS 4bet even with a worse set odds
PS: the other possible hand 3bet call 4bet is 76s, 56s, but that style is not often in stars now.
based on the combination, you need 40% pot odds
, think that the winning odds is closed to 39% -40%
but VS fish, I would find a good edge to play that 1% edge is not enough for full stack.