For this achievement you will need to feed an ocelot raw fish to tame it. However, finding an ocelot and making it willing to be tamed can be a rather difficult process.
Ocelots only spawn in jungle biomes. These are easy to identify because they have trees with vines and cocoa beans. Seed 1027331069 will put you right in the middle of a huge jungle.
If you don't know how to fish
will explain it all. You should only need 1-2 fish to get this achievement, but to be on the safe side I'd get 6 since finding ocelots is rather difficult, and you don't want to run out of fish.
Once you have fish, you need to find an ocelot. Make sure the game is set to at least easy difficulty and just walk around the jungle. Kill all of the other animals you come across, and if you want, torch large sections of it as you're walking though (with flint and steel) to make it easier to navigate and see. If it starts to get dark and you haven't seen an ocelot, just switch the difficulty to peaceful, place a bed in the middle of the jungle, sleep, and then switch the difficulty back to easy and continue searching during the day again.
Now once you come across an ocelot you need to move slowly while approaching it with raw fish selected in your hand. Do not turn suddenly, and make sure to hold shift when you are walking to sneak as best you can. Your goal here is to get within 6-10 blocks of the ocelot
. If you are further away the ocelot will not enter "begging for food" mode. If you are too close, the ocelot will become scared and will run away quickly. If the ocelot runs away quickly, it cannot enter "begging for food" mode for ~15 seconds. So follow it and try to remain within this range of distances to trigger "begging for food" mode.
When the ocelot enters "begging for food" mode, it will turn towards you and approach you slowly DO NOT MOVE AT ALL
. The ocelot will approach you fully, and you just need to right click with the fish in your hand to tame it (when it's within a few blocks). If it's successful the ocelot will turn into a cat with a collar.
However, there is only a 66% chance taming is successful upon feeding an ocelot a fish, so you may need to repeat these steps multiple times.