fish

[missy101]

is it true that if you pull a fish backwards it will drown?

[wildwood]

Unless you are prepared to tie it by the tail to a speeding jet boat when you'd physically damage its gills, no.

Most fish breathe by sucking in water which moves over its the many lamellae of the gills extracting the oxygen from the water in the same way as our lung do from air. IF you drag it backwards through water it will still be able to suck in water.
You can however drown fish by keeping a few in a receptacle such as a bottle or jar with a narrow top where the surface area is very small. The fish will effectively use more oxygen from the water than can be replaced by the small surface area so in fact suffocating the fish.

Some fish such as sharks do not suck in water but rely on the actual water flow through their mouth to oxygenate their gills. They are easily spotted because they have gill slots - usually 5 or more, rather than a single gill cover as with most fish.
btw. If I may dispel another myth while we're on the subject of fish. Sharks do not drown when they stop swimming, many species in fact rest on the ocean floor. These rely on the current for the water flow. They do drown when they are caught in nets however because they can not face the right direction while caught up, in the same way as dolphins can not rise to gulp air from the surface when they are caught in nets.