They're very prone to internal parasites.
I even got them from a reputable source, overkill on filtration,UV,live plants,etc.
Daily 20% WC's would stress my lil ones out too.
I guess some are stronger then the others, it's so hard when you just choose by the color of the fish too.
Was told to get a group to have a better chance since the stronger one would pull through.
Nada...
Good luck with your survivors.
If you decide to add another EBJD getting 1(or2)over the size of 4", is usually considered "past the danger zone".
To think I bought 4 over getting a Thai Silk Flowerhorn.
I'm positive the Thai Silk would still be around if I decided to get that fish, & I got the UV because of the EBJD's.
It's all good I use the UV on my main tank & it's crystal clear.
That's the price/risk we pay to have pretty fish, & IMO is all part of the hobby.

You save some & you loose some.
