My White baby Goldfish Died

Is it a Fantail Goldfish or Veiltail Goldfish ?

Two weeks ago I bought 2 pairs of Pearlscale Goldfish added a small white Goldfish which I'm not sure Fantail or veiltail. I liked him/her because even though still a baby those tail fins were nice and long and this guy had a totally white body not a single dot of other colors like gold or black.

Until yesterday he was so active and happy eating food and munching stuff on tank floor. But yesterday morning I noticed he was staying on surface of water. I didn't bother about it because Pearlscales were on surface too eating pellet food. When I checked after an hour poor guy was dead. I couldn't find a single cause for death. He was healthy and had no illnesses. Pearlscales has problems like one had a anchor worm etc so I treated everyone but this guy had nothing.

Also water quality was not bad. 48 hours old water and I added fish only 10 hours ago. Plus all other fish were doing great. Only thing I can think of is an oxygen problem because I have stopped air pump for an hour. But others were not showing any distress and also when this guy had used to it for days. Usually if a Goldfish die without a apparent reason its usually something do with water condition but water was find. You can use API Freshwater Master Test Kit to test water quality and it's the best one out there and I think everyone should have one. But in my case result was fine.

I was so depressed about this for whole days so in evening I went to petshop just to see if I can have another white Goldfish or a pair. They were sold out but there were few left in tank so I took a pair. I don't think they are great like the last guy but I bought them. This Petshop owner is a lazy bugger who don't care about fish. These white Goldfish were in a tank with White Skirt Tetra. 

But there was new stock of Oranda and Black Moor. Baby size fish but there were some really cool looking fish. I bought one Black Moor and pair of Oranda which looks bit like RedCaps. Not high quality but this pair had red on ther head and white body. Nice bridge red. There were few others who looks nice a small goldfish which looks very much like a Panda Goldfish and another one with beautiful long tail. Many I will go there again in few days and take those 2 home too.