Keaf, Murk of the Ghoti - Phantom Nightmare

If a Fish monster is on the field: You can Special Summon this card from your hand. If a monster(s) is Special Summoned to your opponent's field (except during the Damage Step): You can target 1 of those monsters and 1 of your banished Level 6 or lower Fish monsters; banish both that opponent's monster and this card, and if you do, Special Summon your targeted monster. During the Standby Phase of the next turn after this card was banished: You can Special Summon this banished card. You can only use each effect of "Keaf, Murk of the Ghoti" once per turn.