When they get full grown they (chinese algae eaters) will likely harm your fish so I would return it and get the Otto's. I have had them and my betta's never killed them. PM Bombalurina and she can give you great info on both and she will give you the straight facts and not opinions. Chinese algae eaters can get pretty big. Here's a quote from someone who sells them with the web address to follow.
Many people, including myself, keep this fish with a very wide range of other fish and it is commonly kept to reduce the algae in community aquariums.
But some individual fish of this species will suck on the sides of mostly larger slow moving fish. This can be very damaging to these fish and will often lead to their death. Although even small Algae Eaters will sometimes do this, it is likely to become more of a problem as the Algae Eater becomes larger. Algae Eaters also become increasingly territorial as they get bigger.
Very large Algae Eaters have been reported to swallow small fish like Neon Tetras. I have never observed this myself, and would not expect it to happen with the usual size of Algae Eaters we get.
With all the problems associated with this fish, the question might fairly be asked “Why do you sell them?”
At one time I stopped getting them, but my customers wanted me to have them. They are the most popular algae eating fish. Personally I prefer the Bristlenose Catfish, but Bristlenose Catfish are not always available and tend to be about twice the cost of the Algae Eater."