Need help resolving aggression from dwarf puffer/ getting them to eat frozen

[BigOunce]

A few days ago I picked up 2 dwarf puffers for my fairly planted 10 gal tank, which also has an otocinclus. I believe one is male and the other female baded on appearances, but I'm not sure if they are mature enough to properly sex. I've been putting in pest snails which they go after, but whenever I have tried frozen blood worms or brine shrimp the most they will do is peck it once and swim off. After the first day, the smaller of the two (the male?) began chasing the other whenever it would get close. The larger of the two has shown no aggression and had originally been staying close to the other until it started getting chased off. This is my first time owning dwarf puffers and I am not sure what is normal behavior for them. If there is any advice on anything I can do or change to reduce aggression and get then to eat frozen foods, it would be greatly appreciated. I will provide pictures of the puffers and tank below

Male?:

IMG_20231201_201428_(400_x_600_pixel).jpg

Female?:

IMG_20231201_200649_(400_x_600_pixel).jpg

Tank:

IMG_20231201_201531_(600_x_400_pixel).jpg

[Pufferpunk]

DPs are best kept in groups of 6 or more.
https://www.pufferfishenthusiastsworldw ... vancoricus

[BigOunce]

Moved them to a fairly planted 20 gal long, and also picked up 4 more puffers that are about the same size. In the original tank, the bully would chase and try and nip at the other but never caused any visible fin damage. While in the 20 gal, there was one puffer that was consistently chasing/nipping the others and actually causing visible damage to the others' fins. I ended up moving him to his own tank after adding more plants/hides didn't deter him. I thinking of reintroducing him tomorrow to see how it goes, but am unsure if that is a good idea. I'm already planning on getting more plants for the tank but don't know if it'd help since it didn't make a difference last time. The other 5 puffers seem to get along fairly decently and i only see an occasional short chase. Anyone have an idea on how to resolve the aggression from the lone puffer or would setting him up his own permanent tank be a better option?

[Pufferpunk]

You may just have a single bully on your hands and need to keep them separated. The tank should be densely planted to remove lines of sight. Do you know the ratio of male to female?