We are going to create a single-page web app that simulates an aquarium with a crack that bursts.
 The simulation will include:
   - Water escaping through the crack with flow strength based on water depth
   - A curved water jet affected by gravity
   - A spreading puddle that collides with the room boundaries
   - Fish, rocks, plants, and a floating toy with different densities and reactions
   - Objects transitioning from underwater to airborne and then to floor collisions
   - Fish swimming against the current before being swept out
   - Glass fragments with angular velocity, collisions, and water resistance
   - A visible waterline that lowers continuously

 We'll use HTML5 Canvas for the simulation.

 Steps:
 1. Set up the HTML structure with a canvas and controls.
 2. Write the CSS to style the page.
 3. Write the JavaScript for the simulation.

 We'll break the JavaScript into parts:
   - Physics parameters (gravity, density, drag, etc.)
   - Objects (Water, Tank, Crack, Fish, Rock, Plant, Toy, GlassFragment)
   - Simulation loop
   - Event handling (for dragging the crack)

 Let's design the simulation:

 The aquarium is a rectangular tank with water. The crack is a vertical line on one side (right side for simplicity).
 The user can drag the crack up and down to set its vertical position.

 When the crack is triggered (by a button or automatically after dragging), the crack bursts and water starts flowing out.

 We'll model the water as a grid of particles for the jet and puddle, but for performance we might use a simplified model for the water flow.

 However, note: simulating water with particles for the entire tank might be heavy. Instead, we can model the water level in the tank and the outflow using fluid dynamics equations, and then use particles for the jet and puddle.

 Approach for water:
   - The tank has a water level that decreases as water flows out.
   - The flow rate is proportional to the square root of the depth of the crack (Torricelli's law: v = sqrt(2*g*h), where h is the depth from the water surface to the crack).
   - We'll simulate the jet as a stream of particles emitted from the crack with initial velocity based on Torricelli's law and then affected by gravity.
   - The puddle will be a collection of particles that spread and collide with the boundaries.

 For the objects inside the tank (fish, rocks, plants, toy):
   - They are affected by buoyancy (density relative to water), drag (in water and air), and currents (water flow near them).
   - When the water level drops, they may become exposed and fall to the bottom of the tank or be swept out with the water.

 For glass fragments:
   - When the crack bursts, glass fragments are generated with random velocities and angular velocities.
   - They are affected by gravity, drag (in water and air), and collisions.

 We'll need to manage:
   - The tank boundaries (glass walls and floor)
   - The room boundaries (outside the tank) for the puddle and objects that are swept out.

 Let's outline the HTML structure:

 We'll have:
   - A canvas for the simulation
   - A button to trigger the burst (or maybe trigger after dragging)
   - Instructions for the user

 We'll allow the user to drag the crack vertically along the right side of the tank.

 Let's code accordingly.

 Note: This is a complex simulation. We'll simplify some aspects for performance and clarity.

 We'll use:
   - Canvas for drawing
   - RequestAnimationFrame for the game loop
   - Mouse events for dragging

 Let's start by writing the HTML file with inline CSS and JavaScript.

I've created a comprehensive aquarium fracture simulation that includes all the physics features you requested. Here's what the simulation includes:

**Key Features:**
- **Draggable crack position** - Use the slider to position the crack vertically before starting
- **Realistic water flow** - Flow strength depends on water depth above the crack, decreasing as the tank drains
- **Curved water jet** - Particles follow realistic trajectories affected by gravity
- **Object physics** - Fish, rocks, plants, and toys with proper density, buoyancy, and drag
- **Glass fracture dynamics** - Fragments with angular velocity, collisions, and water resistance
- **Waterline lowering** - Continuous water level decrease rather than instant emptying
- **Fish behavior** - Fish attempt to swim against the current before being swept out

**Physics Implementation:**
- Vector-based physics engine with gravity, buoyancy, and fluid dynamics
- Different object densities affect their behavior (rocks sink, toys float)
- Water current affects objects based on their position relative to the crack
- Smooth transitions between underwater and airborne motion
- Realistic floor collisions and friction

**Visual Elements:**
- Glass aquarium with visible water surface
- Animated fish with swimming behavior
- Detailed rocks and aquatic plants
- Floating rubber duck toy
- Glass fragments with reflections and fading
- Water particles with proper flow visualization

The simulation starts with positioning the crack, then shows the crack forming before bursting dramatically. You can observe how objects react differently based on their properties and how the water flow evolves over time.

The file is completely self-contained with no external dependencies - just open `index.html` in a web browser to run the simulation.