This fight is simple.
You will still be finding portal fragments throughout this chamber but the main focus is defeating the flame newt.
To defeat the newt you need to bait it into eating the blue glowing crystals throughout the level. You will need to knock them down first by slamming the fish into them. Once they are down simply bait it into biting them by sitting next to them.
There is a small hole through one of the pillars you need to ragdoll through to get a fragment.
This fight takes some patience.
You will still be finding portal fragments throughout this chamber but the main focus is defeating the golem.
To defeat the golem you need to bait it near one of the buildings with a red obelisk. Now go up to the top of the building and use the obelisk to equip the saw. Now jump on the golem's back and hit the blue crystal on it's back with the saw. You can use the grapple to slam the fish into the eye up front to stun it temporarily if needed.
This area is very large and maze-like. Use the grapple to move around faster.
If you hit this you will die.
If these hit you you will take damage and be likely knocked off a platform.
If the player is in sight, this will turn towards the player and fire deadly bolts at them.
These little guys just want a hug.
Unfortunately for you they are made of acid...
These guys are pretty harmless. They will jump at you if you are close and latch onto you.
They will deal damage to you over time, but they are needed to push down on pressure plates with a scale graphic.