I am not sure of the reason, but most of the Tarot series fish seem to hold something in their right hands. Knight of Swords is of course, holding a sword in his right hand... You can purchase a Knight of Swords at 29 fishbucks - considerably affordable perhaps?
Personally, I do not like snakes (or any of its wriggly relatives) but this Serpens looks more like a monkey to me rather than a snake. Serpens is also priced at 29 fishbucks.
Just in case you do not know where to purchase these two fishes, I have put up some quick guidelines below...
This is the default interface of your aquarium. On the right side of the aquarium, there is a house-shaped icon (with a tiny fish on the roof). This is the Store (I have just decided to call is the Store, as Happy Fish has not given a name to this icon). You will be able to purchase fishes, fishbucks and coins from the Store.
After you tap on the Store icon, two more icons will appear - one is for purchasing fish, another is for purchasing fishbucks and coins.
Remember to release your new fishes into your Display Tank after they have produced gems. Happy Fishing!!





