Before rushing out to buy any spiny eel, be sure and read up on them first. CFC has written a nice index card for them
here, though be sure and read my
comment at the end about which species is which.
Macrognathus siamensis is probably the most widely traded "peacock spiny eel" though there are others.
These fish are intelligent and friendly (once settled in) but they are tragically abused in the hobby. Most die very quickly. There are two rules to follow if you want success, particularly with the smaller species: Firstly, always, ALWAYS, keep them in a tank with sand; NEVER gravel. Gravel is a death-sentence for a small spiny eel. When they try to burrow into it, they scratch themselves, and eventually they contract an incurable bacterial infection that invariably kills the fish.
Secondly, don't keep them with catfish or loaches. Spiny eels forage at night and eat small animals like bloodworms and tubifex. If there are catfish or loaches in the tank, the food will be taken before the spiny eels have a chance. Result: starvation.
Beyond that, some general advice is to use floating plants as much as possible because these fish like the shade. The more shade in the tank, the more they will swim about by day. Also keep the tank covered, because they jump, and make sure they cannot swim into the filter.
As far as tankmates go, some spiny eels do best in groups, while others are highly territorial. Macrognathus siamensis usually does well in small groups, and the more you keep, the more you will see them. One or two specimens tend to be very shy. So, your first thought should be to keep 3-4 of the one species before adding anything else.
I would strongly recommend midwater and upper water oddballs and companions, so as to minimise competition for food. In other words, look to things such as glassfish, butterflyfish, halfbeaks, Asian killifish, and so on. Suitably sized barbs and tetras could be used, too. (Spiny eels will eat tiny fish, so avoid neons, guppies, etc.) The only bottom dwellers worth considering would be similarly slow feeders, such as gobies and flatfish. What I wouldn't keep them with are catfish and loaches, as mentioned above, nor with aggressive or nippy species, such as cichlids or puffers.
Cheers,
Neale
