FR50 AT 4b pot vs fish

Poker Stars, $0.25/$0.50 No Limit Hold'em Cash, 9 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

BTN: $59.67 (119.3 bb)
SB: $25 (50 bb)
BB: $51.15 (102.3 bb)
UTG+1: $50.50 (101 bb)
UTG+2: $69.84 (139.7 bb)
MP1: $74.64 (149.3 bb)
MP2: $29.18 (58.4 bb)
Hero (MP3): $56.01 (112 bb)
CO: $41.09 (82.2 bb)

Preflop: Hero is MP3 with T A
2 folds, MP1 raises to $1, MP2 folds, Hero raises to $4, 4 folds, MP1 raises to $7, Hero calls $3

Flop: ($14.75) 3 3 A (2 players)
MP1 bets $0.50, Hero calls $0.50

Turn: ($15.75) 7 (2 players)
MP1 bets $2.50, Hero calls $2.50

River: ($20.75) 8 (2 players)
MP1 bets $2, Hero raises to $7, MP1 calls $5

I think he has JJ-KK most of the time, some AA and almost no air.
So I have to raise at some point, I thought that a river raise is the best. If I raise before he may get scared and fold.

only 15 hands, vpip 60, pfr 20, wtsd 33, w$sd 0
limp-call 100, so definitely fish...