Addon: Fish Catchers

The FishCatchers Add-On adds 1 new modular block, with 3 upgrades to Minecraft! Here is what the block (with and without upgrades) looks like when empty, and when it has caught something: 

They can be water-logged with a water bucket (and un-water-logged with an empty bucket), and they require being in water/water-logged to catch fish.
Here is what they look like while water-logged (and while they have caught something):  note: they don't require a 3x3 of water around them, just water inside them

There are 4 different types of fish catchers.

• Normal - Only catches fish
• Junk - Only catches junk (leather, bones, etc.)
• Treasure - Only catches treasure (enchanted books, saddles, etc.)
• Auto - Catches everything, and is automatic

These upgrades all catch fish at different rates.

• Normal -> 16 seconds
• Junk -> 14 seconds
• Treasure -> 20 seconds
• Auto -> 18 seconds

For comparison, manual fishing takes between 5-30 seconds to catch a fish, and with lure 3, it is 15 seconds shorter, 
so manual fishing is normally significantly faster than a couple of fish catcher blocks.

To apply an upgrade, simply right-click a normal fish catcher with one of the 3 upgrades. When you break an upgraded fish catcher, 
it drops the normal fish catcher, and the upgrade you applied to it.
(Note: each fish catcher can only have 1 upgrade applied at a time)

To collect a caught fish, simply walk on top of the block.

For the auto upgrade, they do not require this, as they spit out the item above them. You can either manually collect the items once spit out, 
or you can use a system like this to auto collect them: 

Crafting