94Roarge,
Please send me a picture and I can help identify the Cone type.
You need to identify exactly what Cone snail you have to determine what they eat. They are very specialized with what they prey on; their harpoon like radula and venom is designed for their target prey. I used to catch and keep them in tanks when I lived in Hawaii.
The most common species preyed on certain types of polychaete worms; some only targeted bristle worms and others only fan worms. They were the hardest to feed due to this specialized targeted prey.
The snail or molluscivorous species were the second most common and pretty much ate all marine snails. I had Textile, Marbled, and Penniform Cones and they ate any Cowries, Turbo, Conches, and even other Cone shells. I have a nice shell collection due to them. Most of the Cones with a tented pattern are in this family.
The fish-eating or piscivorous species were uncommon, but ate any live fish they could harpoon. Blennies, gobies, and any small fish they hunted. I actually fed them guppies and small tilapias I caught in local streams and ponds. Held the guppies in forceps and the Cone extended its proboscis, stung and pulled in the guppie. The most common I kept were Cat Cones and Striated Cones. Please note they will sting fish to big to eat, so larger aquarium fish can be targeted as prey.
The fish-eating Cones have the most potent venom but it takes a lot to get stung. You would have to handle them for a while and stress them to extend their proboscis to get stung. It is easier to get stung by Lionfish, so if you leave them alone and not handle them excessively you are good.
Kevin