Custom Tropical Fish Spawn Egg Spawns Random Fish After Being Put In Inventory

I made a custom tropical fish spawn egg, to try and make a clownfish:

/give @p minecraft:tropical_fish_spawn_egg{display:{Name:"{\"text\":\"Spawn Clownfish\"}"},EntityTag:{Variant:65536}} 1

It worked fine, but if I put the egg in my inventory, then took it out again, and used it, random fish would spawn. I tried it with other color and pattern combinations, to the same result.