When this card is Normal or Special Summoned: You can banish this card; Special Summon 1 Level 4 or lower Fish-Type monster from your Deck, except "Beautunaful Princess". You can only use this effect of "Beautunaful Princess" once per turn.
You can summon a Hammer Shark and activate its ability to special summon Beautunaful, this can then be banished to search for other low level fish type monsters, and in a Hammer Shark deck, you will have plenty of options to summon. Alternatively, you can banish Beautunaful to summon another Hammer Shark and activate the second Hammer Shark's ability to special summon another monster from your hand, giving you 3 monsters in a turn.
This lets you special summon Beautunaful without using up your normal summon, but only when you have no monsters on your field. Remember to special summon a monster by activating this spell card when it's on the field, instead of normal summoning first before activating, which will not work.