hi, I can help out with dragonet care a little bit.
I have been breeding marine and freshwater fish for about 15+ years now.
Most pet stores that carry these fish do not provide any live copepods or actively train them on live foods. Which is the root problem why they don't survive or won't eat.
All mandarinsin the trade are currently wild caught, as my company ( ShrimpZoo currentlyis the only one actively breeding them.
The wild caught fish are either poisoned to stun them ( cyanide)
Or they are caught with mini spear guns, harpooned into the side or fins.
In the case of poison as the previous member stated his fish was lathargic and wouldn't eat, yet nice and fat. That is how the poisoned fish act.
Sadly they tend die shortly after this.
The speared fish are usually okay unless the were harpooned in the spine, in which case they can suffer from spinal injuries but usually still eat and are active, however they die sooner rather than later.
In my experience 80% of wild caught mandarin gobies will die very soon.
Unless you see your Lps training their fish to accept frozen shrimp or have a large copepod culture don't buy your fish at that store.
When I first started to breed them, 8 out of 10 died within a day or two.
I have tried many Lps and online sites, but quality mandarins are extremely hard to find. most experts say they are the marine fish with the heaviest die off in the trade.
Hopefully more companies will Aqua culture them in the future, as the current trend is devastating to these fish. It's sad because Aqua cultured mandarins are very hardy and easily eat pellets and frozen foods.
You can check my YouTube videos or website for more info on how to train them to accept frozen foods and tips to care for them.
ShrimpZoo