You know that there are fish in the Jordan river, right?
Do you know enough of the Bible to know that it says you can eat any fish that has both scales and fins?
The picture is a group of catfish that are gathered near the place for water baptism, in the Jordan river. Catfish are bottom feeders which do not have visible scales. That is, they are not kosher. Most Jewish people don't eat catfish and if you remember, the Jordan river flows through Israel. That is probably the most logical reason that the catfish here can grow to over a meter in length.
They don't bother the tourists who come here for a baptismal service. They prefer to go out to the middle of the river and sit on the bottom. However, some of the tourists throw pieces of bread to them and they come up to get the treats. That is what we see here.