When a Fish, Sea Serpent, or Aqua-Type monster is Normal or Special Summoned to your side of the field: You can Special Summon this card from your hand. This card cannot be used as a Synchro Material Monster.
Well yeah, of course. A Tuner that can't be used for Synchro Summon period would be useless as a Tuner.
Besides, this is Zexal anime early card, first appearing in episode 10. Look at Gagaga Magician for example, some of the early Zexal cards gets "no Synchro Summon" restriction in OCG/TCG because Konami wants to promote Xyz, not more Synchro spam.