The new you comes back to reality, still covered with the strange, transformative fungus, but no longer encased and trapped by it. You take a deep, gasping breath, filling your lungs and pulling air through slits in the side of your neck. Your hands reach up to feel them, new gills, delicate but sturdy, rippling open and closed in rhythm with your breath. You look down to your foot, where your other body should be, but it's been fully absorbed by now. Instead the foot has become a strangely beautiful mixture of fish and human, covered in shimmering trout scales of green and red and white, with thin tapering toes connected by almost amphibian webbing, built for swimming down roaring rapids and gliding along gentle streams.
Going up, pulling your oddly intact pants out of the way, you see your leg has changed to match, the inside of your thigh a shining white, separated by a red fade from the outer dark green, the side of your leg sporting a short fin that winds its way up your leg and ends at just below your hips. The new additions flutter in the flowing stream, like someone stroking up and down your leg. Your oddly curvy leg. In fact, your arms look pointedly feminine as well, slender and gentle with webbed fingers capped by sharp short black claw-like nails and dark green scales along your hands. Looking down to your legs again, you get a suspicion in the back of your mind, one that going further up quickly confirms.
You zip open your pants, pull down your underware, and wince. No two ways about it, you're female now. Instead of the human shaft and balls you woke up with this morning, your new body has a decidedly fishy take on a woman's entrance. The white, notably soft scales of your stomach and inner thigh lead up to a set of wet, shining lips, dark green and ridged like fins, but still very sensitive as your wandering finger quickly finds. You pull it away, and note how oddly calm you are about this new development. The smaller, newer part of you certainly thinks it makes sense, and that seems to be helping your human mind adjust. When a human man and a female trout meld together, what else could you expect? Certainly better than turning into some weird human-skinned fish, at least.
You continue taking stock of your new form. Your hands slip under your shirt and feel the soft white of your belly scales, noting that you still have your belly button for some reason, and a powerful set of muscles hidden just beneath a layer of baby fat on your abs. The sensation of your tapered fingers stroking against them makes you squirm in delight, wriggling your hips involuntarily. Apparently fish can be ticklish.
You move up to your waist, curving into a subtle hourglass shape that's emphasized by your new coloration, white and green scales following a red border that brings to mind a dress opened down the middle, the outer green spotted throughout with black markings almost like a leopard's. As you brush the thinnest point of your waist, which peeks out between your shirt and pants, you discover a second set of gills on each side, tougher than the ones on your neck but still pleasantly tender. You stroke one with a scaly finger, and it thrills you like a soft, gentle hand held against your throat. You continue upward to your new chest, rolling up your shirt, and wonder how it wasn't the first thing that caught your attention. There, standing proud on your new frame, are a pair of soft, white humanoid breasts, capped with pinkish-red nipples. They're sizable but not massive, maybe a large B-cup or small C-cup, and lay sleek against your frame as befits a natural swimmer's body. You can't help but feel them up, soft but dense and tight, with barely any sag to them. The webbing between your fingers brushes over a nipple, and you almost double over from the jolt it sends down your body.
As you look down past these new additions, you see that strange purple fungus letting go of your body and floating away down the stream. With that, you lose interest in exploring your body right now, rolling down your shirt and zipping your pants closed. Enough feeling yourself up. Time to head home before something else weird happens.