By my calculations the solar panels, assuming they're putting out their max rating 8 hours a day, ignoring costs of batteries and other supporting equipment and going by the best prices I could find...They would pay for themselves in 15 years and need replaced in 20 years. The supporting equipment some would last far less than that(Batteries) or longer but I'd say bet on replacing the entire system every 20 years...So, no, not worth it unless you don't have access to electricity from any other source. Better than diesel, worse than wind if you are in a windy area...
For a marine tank you'd be better off instead of powering the lighting by solar panels you could set them up under a skylight or solatube, maybe set up some kind of mirror system with sun tracking. That'd be FAR more efficient.