Poker Stars $1/$2 - 6 Players -No Limit Hold'em

BTN ($183.20)

BB ($240.90)
UTG ($565.84)
MP ($196.81)
CO ($110.90)

Pre Flop: ($3) Hero is SB with (SB) Ad7d
UTG folds , MP calls $2, CO raises to $8, BTN folds , Hero calls $7, BB folds , MP calls $6

in real game
MP limps, CO isolates, SB flats isolating. MP here is obviously a fish so Hero here just flats and gets in to multiway. I'm curious is it better to just flat, extracting value from fish or 3bet/fold to immediately pick the pot. Or just 100% folding is better? This is not just about A7s but also other hands in pot involving fishes. Is it better to just call against isolating limping-fishes in SB?