Fascinated by ocean life, Trent wants to put a saltwater aquarium in his bedroom. He needs to make sure he buys a big enough tank to grow his collection of fish over time.

To determine if \( x \) (the number of fish) and \( y \) (the tank size in gallons) have a proportional relationship, we can check if the ratio \( \frac{y}{x} \) is constant for the given values.

Calculating the ratios for the provided values:

1. For \( x = 1 \): \[ \frac{y}{x} = \frac{17}{1} = 17 \]

2. For \( x = 2 \): \[ \frac{y}{x} = \frac{34}{2} = 17 \]

3. For \( x = 3 \): \[ \frac{y}{x} = \frac{51}{3} = 17 \]

4. For \( x = 5 \): \[ \frac{y}{x} = \frac{85}{5} = 17 \]

Since the ratio \( \frac{y}{x} \) is constantly \( 17 \) for all the pairs of values, we can conclude that \( x \) and \( y \) do indeed have a proportional relationship.

Therefore, the answer is: yes