He was most likely fine if it was feeding, but normally that is a sign of something bad. Sometimes when they come into a fast temperature change they will bloat up and it causes them to swim upside down for a while. It goes away and they're fine. The missing pectoral is one way Fisheries marks steelhead for identification of year, rearing facility and stocking location. They do just fine with a pectoral fin clipped off. As to dipping him up, yeah that's illegal taking.