Do you gain muscle from swimming?

I apologize if this is a dumb question, but I have gotten mixed information from people.

Since there is full body resistance in the water, I assume you DO gain muscle. I have definitely felt sore after doing laps and it seems like my arms are stronger and are toning up since I started.

The biggest reason I ask, though, is that I actually gained weight instead of lost weight after starting to swim regularly. The weight is inching back off but it feels like it's taking forever.
I have continued to go down in inches, though, which makes me think (again) that I may have gained muscle.

I guess I just want to know that I am not crazy here.

I don't believe so. Not anything substantial anyway. Increase muscular endurance sure. That is likely what caused the soreness.

Huh. I find that surprising.

Every thing I read says that swimming is both cardio and strengthening. It tones your body so I am surprised it doesn't add muscle.

Or maybe I am getting all my terms confused...
"strengthening" VS. "toning" VS. "muscle building".

Any other insight would be greatly appreciated!

Strengthening muscles requires lifting heavy loads. Swimming doesnt offer enough resistance for that. I would guess that the strength I need to swim with my arms is equal to maybe lifting a 5lb dumb bell. I will not increase my strength by doing hi-rep lifts with very light weights.

Toning, damn I hate that word. Usually refers to loss of fat resulting in exposure of existing muscles. swimming can burn calories, thus lowering bf% thus resulting in muscle definition

Muscle building requires a caloric surplus accompanied by strenuous strength training using progressively higher loads. Swimming will not do that.

Its a good exercise. But is shouldn't be considered part of your resistance training.

Let's not get ahead of ourselves and say that swimming does not build muscle. It can definately build muscle. Of course, that depends on the type of swimming you do. In a pool you will most likely not build much muscle but you can burn a lot of fat and help trim up your body.

If you are swimming in the ocean, for instance, you may be fighting current for the duration of your swim in which case you use more resistance and have a chance to build more muscle. I wouldn't say that swimming is the most effective way to build muscle but if you do the right kind of swimming you can certainly benefit.

Bleh. Its just my opinion. Luckily I'm not paid for it so I can be wrong. I agree, as I stated above that it is a good exercise and it will help burn calories. Assuming that the poster is in a caloric deficit though I don't think swimming laps will produce the kind of muscle gain it would take to make a noticeable weight increase on his scales.

I'm not past being teachable though if someone has any sources.