i dont find the species on the internet, but is a assassin bug because he have the proboscisWhat species of bug do you have? Are you certain that it is an assassin bug and not some other ant-mimicking species? There are a great many different bugs that resemble ants, particularly in the early stages of their development, and not all of them will have the same requirements. It would be helpful if you could provide the scientific name of your bug - or at least provide some pictures of it.
ThanksYeah, that is not an assassin bug. The proboscis is too long and the antennae are the wrong shape. Assassin bugs have a short, sturdy proboscis. This is the long, slender proboscis of a plant feeder. Also, the antennae of this bug stay pretty much the same diameter (or may even get slightly thicker at the tips) while those of most assassin bugs taper toward the tips.
Consider, instead, one of the Alydidae (Broad-headed bugs) like @aaarg suggested. Compare to this one: https://www.alexanderwild.com/Ants/Natural-History/Ant-Mimics/i-Hp3F9Wg/A. It is likely to feed on plant seeds, which it will pierce with its proboscis to suck out the fluids. The specific variety of plants it will feed on may vary from one species to another, but consider what types of plants were around in the area where you found it.