time traveling so you can make around 5 mil a day and you get the weeds away in an half hour it is worth it:D or use this cheat i founded i out myself :D :
his is a very good topic becose you can learn to catch those big fish the easy way.
first get an net from nook. Then go to the beach-sea and watch till there is an fin out of the water like all shark movies and cartoons. then if there is not a fin ou tof the water do this: first use your net and get all non-finfish get swim away by doing hit them with the net in the water. Then hit all fish away until you get a shark with a fin out of the water. the fish is very big and there is an huge shadow under the sea and a fin out of the water. stay hitting all little or non-finfish away till ther is a finfish. then get you fishing pole and fish them al. i got with this trick: 2 ocean sunfish 1 hammerhead shark and 1 normal shark on 1 day!!! i put them in the water or sell them or give them to the museum.
hope i helpep :P happy finfishing:D