Well i kept both tropicals and marine fish and would say no.
Tropical I’ve kept numerous times. I’ve found that the water often smelt when i was younger and my last tank which was just over 1 yr ago seemed to be cursed and would only ever keep 3 mollies and more fish and they would simply perish. The last tank which an Interpet FishPod X 48litre it wasn’t a bad tank and was probably the best that i have kept, i found that algae was kept down with the use of some japanese moss ball. Water changes where frequent but when ever i went to my local fish shop I’ve always craved marines.
I decided to sell the Interpet FishPod X and jump into marines. My first marine tank was a Rio 180 which was setup on a budget of around £500. I went for this after numerous people saying bigger is better. As if you have any water issues it will take more time to take affect, on the other hand you have more water to change and address should anything go wrong.
My current D-D 24G has been a god send, and has never given me any issues. When i moved the water over from my Jewel aquarium Rio 180 there was a slight Phosphate issue which did carry over slightly, but with frequent water changes and a hand full of cheato in the rear chamber seem to sort this and i now have a lovely clean tank.
fortnightly water changes of around 3/4 gallons take place and with this i also change my RowaPhos using a 2 heaped tea spoons worth. Ok changing it fortnightly is more than advised but the sight of hair algae is worse in my eyes, so i’ll pay the extra.
The tank really requires little maintenance over the water changes, maybe a trim back of the cheato every few months, but that’s really it.
So keeping marine fish in my eyes is no more difficult than keeping tropicals