I don't believe so. Now, the little (small) blued in arches all around probably are. And I'd even say the lowest large arch right above and right of the hard bottom object most likely is, too. IMO, the three "taller" arches though aren't fish. Your little detail box is kind of right in the way (LOL), but fish don't typically arch (trailing) all the way to the bottom like these 3 signals do, especially that uniform. Another clue is the hardness (heavy yellow coloring) of the last two arches. They're so reflective you get a little double echo patch of pinkish red straight underneath each arch down toward the bottom (twice the depth of original). Fish don't do that.
It looks very much like something cabled down there. I've had similar type "arches" when idling through marina areas where they have cables running at angles out toward the bottom of the lake holding docks and piers in place. Buoy cables could also do that. Anything similar but solid would have more effect on the overall reading, things like pillars or bridge pilings. So I can't say for sure what they are, but my opinion is that they (the 3 trailing arches) are not fish.
-T9