Currently growing 6 dorado catfish. One has been described above. It's about 7"-8" now. Out of three I got from Mark, only two lived, currently at ~5"-6". And three more are from Fish Bolz at 1.5".
My bad luck with dorado lives on. Lost 3 out of current 6.
The biggest guy that I got from Ray Chan about 10 months ago reached 7" from 1.5". Very highly unexpectedly, I've found it sticking out from one of my 12" piraiba's mouth. I thought piraibas prefer prepped foods very much. I guess I could have been wrong.
That's it. I decided to not comm dorados anymore with any other fish. (Same goes for capapretum.)
In quick succession I lost two of the three Fish Bolz' little dorados that were ~2" and ~2.5", up from 1.5" a few months back. Not sure what happened. They started losing balance and breathing heavy and perished over 3-4 days. My guess is they were overrun by some bacterial cultures, perhaps their gills in particular. I got too busy and skipped a few siphoning sessions. They were poor eaters and I'd throw in about 10x more of finely shredded fish than they could eat. Which means I'd have to vacuum the leftovers every 1-2 days. I went for 5-6 days without vacuuming and got this. Hardly can be a coincidence. My laziness killed them, I think.
The third one is still doing visibly ok. The two from Mark Chen are doing adequately too.
The last little guy (from Fish Bolz) pretty much stopped feeding and perished. Had an ~2x spike in hardness over a week and lost it over the following weeks / a month. The beginning of problems coincided with the hardness increase.
If the hardness wasn't directly what did it in, it could have been some pathogen that its immune system couldn't handle in harder water.
Anyhow, down to two dorados from Mark Chen. These have been doing ok.