Why don't most saltwater fish take care of their young like freshwater counterparts?

Subnautica · Apr 17, 2021

I guess I'm ignorant and it's silly to ask this question. But I wanted to know.

I've noticed that most fish (at least in the aquarium trade) do not take care of their young. Most of them only guard the eggs (like clownfish). Once the eggs hatch, the fry are on their own. Meanwhile on the freshwater side, bettas and most cichlids are good parents (there's also a term called mouthbrooding which might be related to this). I was wondering why there's such a difference. Is it all about their natural habitat (reef vs lake) that defines their breeding bahavior?

Doctorgori · Apr 17, 2021

As I think about it, what fish do outside of sunfishes, ana bids, and cichlids... Groupers or relatives maybe?
Edit add...stickleback I think, but its got be a short list regardless of salinity

ca1ore · Apr 17, 2021

There are FW fish that lay and abandon; and SW fish that mouth brood ..... not sure I see much difference.

D E N I N O · Apr 17, 2021

Some marine fish do, Cardinals are mouthbrooders and protect their young before spitting them into an urchin to grow up.

Many species have fry that go into a larvae stage before metamorphosis. What can they really do for those young...

jrill · Apr 17, 2021

Most freshwater fish also eat their young.

Spare time · Apr 18, 2021

It's impossible to categorize all marine vs all freshwater fish in terms of parental investment. This topic is is complicated subject. It is also probably incorrect to say that freshwater commit more parental investment than saltwater.

The ecology (of predators, resources, etc.) interacts with offspring count, breeding age, reproduction interval, fecundity, fertility, reproductive value, life expectancy, survivorship, survival rate, mortality rate, age specific mortality rate, etc. all interact. However, age-specific mortality predicts life history traits much better than the environment does.

Species with high juvenile mortality, adults produce few offspring at a time and spread reproductive effort over many seasons, regardless of environmental stability
Species with high or uncertain adult mortality, opposite reproductive pattern (get them out while you can)