So you're looking for some info on Colomesus asellus... here are some basics you should know about them in order to keep them happy and healthy...
They are probably the most social and friendly of all the freshwater puffers, and are said to prefer living in groups of 3 or more in a tank... expect to have around 75G of space to house 3 and ensure to have lots of plants and or cover for them to explore around...
This particular species of puffer is also known to have some seriously fast growing teeth, so fast growing that some keepers have even said with a steady diet of snails or other hard shelled foods every meal, they still end up having to trim their teeth about every 6months to a year...
So in other words, if you are planning on getting this particular species of puffer, it would be a good idea to get a large colony of ramshorn snails going, since they will go through them like no tmr if fed them regularly, although naturally, as with all puffers, a varied diet is preferred... that also means looking up how to clip a puffers teeth if necessary, since if their teeth get too over-grown, they will no longer be able to open their mouths and feed...
Other info is pretty much the same as other freshwater puffers, keep water as clean as possible, and feed till their belly are slightly round... also, keep an eye out for IP's, since a lot if not most puffers are wild caught, and tend to need de-worming when first brought home...
Anything else you need to know should be relatively easy to search for online...