One Discus from group is growing slowly

[Raimisx9]

Hello all! I'm very new to this forum and new to discus fish keeping! I have a problem with one of my Pigeon Blood discus fish and I hope someone could help me with it!
4 months ago I purchased 6 8cm Pigeon Blood discus from reputable source and everything is pretty good with the fish except that one fish is not growing as fast as the others. It was smallest from the group so he is at the bottom of the hierarchy in the tank, others are sometimes picking on him and scaring him away from food but he still eats and from my point of view he is not very bothered. He is now about 10 cm in size. He doesn't look stunted or ill. His poop is normal.
I doo 30-40% water changes every second day and about 80% on weekends. I feed them twice a day with frozen sea food based diet and dry Hikari Discus food.
My tank parameters are:
400 liters, 5 foot long tank
Filtration 2X1500l/h
Temperature is around 29-30C
NH4 0
NO2 0
NO3 0-5
pH 7.2
KH 4
GH 5

Any help will be appreciated! Thank you in advance!

[LizStreithorst]

It's normal for one in a group to be on the bottom of the totem pole. These are usually the most resilient fish, at least it seems so. They can be valuable fish. Most experienced Discus keepers have one on hand to use as the sacrificial lamb before introducing a new fish or group of fish to an existing Discus tank.

[Oxboy]

Dude, six mos ago i bought 5 the size of a quarter from Macs Discus. I QTed for about 90 days and they got to a good silver dollar size. Put them in the main tank and 4 of them are 2.5 to 3" and growing. The kicker: one of them has stayed a little larger than a quarter despite eating like a horse. He is not picked on and has red eyes, nice fins and a feisty little attitude. But it's perplexing/hilarious that he never grew.

[rkeane]

One of my 4 discus from the same source stopped eating for like 2 weeks, but yet it's the boss of the aquarium - he is still lively, and attacks other fish if they come to its territory. And noticeably, it grew smaller than the other 3.

[LizStreithorst]

Eating and getting skinny or not growing is a big sign of worms. Just sayin'...

[rkeane]

Eating and getting skinny or not growing is a big sign of worms. Just sayin'...

They would have white poo if so, right?