Fishy

Fishy is a virus in the Mega Man Battle Network series. It moves very fast and moves up and down its column until it meets on the same row as MegaMan. Once it does, it charges a little bit before dashing towards MegaMan. Some variants leave a burning trail in the row that MegaMan can burn himself in.

Fishy
 Fishys are green and can move very fast.

Fishy2
 Fishy2s are reddish-orange and can leave a burning trail behind them.

Fishy3
 Fishy3s are yellow.

FishyΩ
 Fishy2s are blue and dash through the screen several times once they start.