The enemies you encounter on the sea get more powerful as the game progresses

Monster Name	Picture	HP/MP	Atk/Def	Special attacks	Exp	Gold	Items dropped
King Frog		160/78	142/92	Chorus	402	350	Regain(100)
Evil Fish		208/76	178/112	Octo Ink, Eight-Legger	664	700	Charm Fruit(60)
Seahorse		239/204	191/119	Whirlpool	1040	1247	None
Moray		261/224	205/139	Bite	1316	1579	None
Perch		483/244	263/204	None	1585	1901	None
Bolt Fish		306/265	236/160	Blitzer	1816	2179	None
Angler Fish		329/287	247/180	Lantern	2080	2495	None
Unicorn		352/308	265/221	Dash	2383	2859	None
She-Viper		377/331	276/221	None	2690	3227	None
Merman		426/377	303/248	Raging Wave, Sleep Javelin	3329	3994	Charm Fruit(60)
Killer Whale		401/354	288/227	None	5693	5591	None
White Whale		452/401	311/252	None	7703	7443	None
Aqualoi		479/426	326/281	Torrent, Sleep Javelin	3997	4796	None
Current		779/426	366/301	Tidal Wave	8097	6796	None