Small sample,seems is a fish by sizings from previous hands.Is bad against fish? it looks like a block bet for cheap showdown.Some opinions about play?

888Poker, $10.90 + $1.10 - Hold'em No Limit - 400/800 (100 ante) - 7 players
Replay this hand on Upswing Poker - https://upswingpoker.com/replayer/aa1mxxvN

UTG: 30,930 (39 bb)
MP: 6,580 (8 bb)
MP+1 (Hero): 15,505 (19 bb)
CO: 12,784 (16 bb)
BU: 20,746 (26 bb)
SB: 52,361 (65 bb)
BB: 15,865 (20 bb)

Pre-Flop: (1,900) Hero is MP+1 with 8♦ 7♦
2 players fold, Hero raises to 1,600, 3 players fold, BB calls 800

Flop: (4,300) 3♦ 7♠ Q♥ (2 players)
BB checks, Hero bets 2,150, BB calls 2,150

Turn: (8,600) T♣ (2 players)
BB checks, Hero checks

River: (8,600) A♣ (2 players)
BB bets 800, Hero raises to 11,655 (all-in), BB calls 10,855

Total pot: 31,910

Showdown:
MP+1 (Hero) shows 8♦ 7♦ (a pair of Sevens)
(Equity - Pre-Flop: 49%, Flop: 81%, Turn: 89%, River: 0%)

BB shows A♥ 3♠ (two pair, Aces and Threes)
(Equity - Pre-Flop: 51%, Flop: 19%, Turn: 11%, River: 100%)

BB wins 31,910