Tutorials/Fish farming

Fish farming is an easy method of catching large quantities of fish and other items by fishing. Most AFK designs involve right-clicking an iron door with tripwire above it, causing fish caught to flow into a hopper and then into a collection chest.

AFK automatic fish farming
Automatic fish farming involves right-clicking a door with tripwire above it and hoppers for collection, with an automatic fishing rod dropper to supply new fishing rods when the previous one breaks.

1.11+
As of Minecraft 1.11, iron doors and trapdoors no longer register the 'use' control, so older designs no longer work. These first designs work with the updated door mechanics.

This is an example of an autmoatic fishing farm that works in 1.11:It is also possible to eliminate the redstone clock used in most pre-1.11 designs:

This more compact design eliminates redstone completely:

Pre-1.11
The videos below show older designs, that do not work in versions 1.11 or higher.

Most compact fish farm for 1.9:

Automatic fish farm:

This version is more compact:

This next one uses an iron trapdoor instead of an iron door.

Semi-automatic fish farming (not designed for AFK)
Semi-automatic fish farms involve detecting the fishing rod using tripwire to close a door while fishing, improving fishing rates. The next video is an example:

Fish collector
This is a basic design using hoppers to automatically collect fish while being very quick and simple to build.

de::technik:Fischfarm