Many fish species reproduce in a similar way to us. We use loads of energy to produce as many eggs as we can so for every male and female we can produces 1000s and 1000s of potential babies. Obviously not all of them will become adult fish but it’s a good strategy that if even only 5% of our eggs are successful that’s still a lot of adults.
It is believed that we might be semelparous (which means you mate once then you die – salmon also do this). This is probably because food aka energy is so hard to find in the deep sea we have to live a long time to collect enough energy to allow us to produce so many eggs.