To determine how many neon tetras the aquarium can house, you will divide the total gallons of water by the amount of water needed for each tetra.
- Total water in the aquarium: \( 1 \times 10^5 \) gallons
- Water needed per neon tetra: \( 1.25 \) gallons
To find the number of tetras:
\[ \text{Number of tetras} = \frac{\text{Total water}}{\text{Water needed per tetra}} = \frac{1 \times 10^5}{1.25} \]
Now, calculate \( \frac{1}{1.25} \):
\[ \frac{1}{1.25} = 0.8 \]
So, now we have:
\[ \text{Number of tetras} = 0.8 \times 10^5 \]
To convert \( 0.8 \times 10^5 \) into standard scientific notation, we can rewrite \( 0.8 \) as \( 8.0 \) and decrease the exponent by 1 for proper scientific notation:
\[ 0.8 \times 10^5 = 8.0 \times 10^{4} \]
Thus, the final answer is:
\[ \boxed{8.0 \times 10^4} \]
This means the aquarium can house \( 8.0 \times 10^4 \) neon tetras.