I still haven't gotten it yet, but I think you just have to buy and sell Scooter Blennys until that final 'Pience of Coral' pops up
Starry blenny
There are 732 species of Blennies. Here is some examples: Bicolor Blenny (ecsenius bicolor), Black Combtooth Blenny (ecsenius namiyei), Black Sailfin Blenny (astrosalarias fuscus), Black-Lined Blenny - Tank-Bred (meiacanthus nigrolineatus), Canary Blenny (meiacanthus oualanensis), Ember Blenny (cirripectes stigmaticus), Fortail Blenny (meiacanthus atrodorsalis), Horned Blenny (hypsoblennius exstochilus), Linear Blenny (ecsenius lineatus), Lizard Blenny (parapercus sp.), Midas Blenny (ecsenius midas), One Spot Blenny (crossosalarias macrospilus), Orangetrhoat Pikeblenny (chaenopsis alepidota), Sailfin/Algae Blenny (salarias fasciatus), Segmented Sailfin Blenny (salarias segmentatatus), Starry Blenny (salarias ramosus), Striped Blenny (meiacanthus grammistes), Tail Spot Blenny (ecsenius stigmatura).
Tasseled blenny was created in 1907.
Portuguese blenny was created in 1836.
Cheekspot blenny was created in 1887.
Tompot blenny was created in 1758.
Montagu's blenny was created in 1758.
Peacock blenny was created in 1810.
Longstriped blenny was created in 1833.
Australian blenny was created in 1988.
Mimic blenny was created in 1857.
Heuvelmans' blenny was created in 1986.