Tropical Fish Variant

Yellow Tail Parrorffish Tropical Fish is not spawning in survival Minecraft. I cought all tropical fishes that have a specific name (Triggerfish, Parrotfish etc.), but i have been unable to find one in my 2 hours search. It can't be summoned with commands on creative either, it instead summons a white kob. It happens on both beta versions of xbox one and androod, as well as standard version

How to reproduce:
1. Find Coral reef
2. Search for Teal-Yellow Dasher (Yellow Tail Parrotfish)

Result:

• Can't find one

Or:
1. Use a command: "/Summon Tropicalfish ~ ~ ~ minecraft:become_yellow_tail_parrot"

Expected result:

• Yellow Tail parrotfish is spawned

Result:

• White kob is spawned