If you have this card in your Graveyard already, Normal Summon another copy of this card so you can Special Summon a second one from your Graveyard. You can use them for a Rank 4 Xyz Summon and avoid it to be banished when it leaves the field.
Similarly, if you have two copies plus another WATER monster with 1500 or less ATK in your graveyard, you can use Salvage to bring one copy of Fishborg Doctor and the other WATER monster to your hand, then Normal Summon the Fishborg Doctor from your hand and Special Summon the second one from your Graveyard.
If you have two in your hand instead, you can discard one with a card effect such as Twin Twisters then proceed with the same combo as mentioned above.
If you control "Fishborg Planter", discard this card as cost to activate the effect of "Fishborg Blaster" and Special Summon it; then, Special Summon this card by its own effect and Synchro Summon a Level 7 Synchro Monster.