the other person that responded seems to be a little confused, since i don't remember you mentioning feeding your frog only worms nor do i see anything related to a heat light.
the main reason for keeping a screen on a cage, which won't really help hold in humidity, unless it is a really fine mesh like window screening, is to keep your pet in and keep foreign objects out. if you have children or other lose pets like cats that can get into the cage, then i would suggest putting a screen on. whether you need screen or not also depends on the height of the tank and the plants as well as the size of your frog. just because pacmans are fat with stubby legs doesn't mean the are incapiable of climbing large leaf plants or jumping short distances, or a combo of both. if the space between the top of the soil and the top of the tank is less than 6 inches and/or you have strong, broad leafed plants near corners in the tank, then i would suggest considering a screen top or different, smaller plants. as for feeding pinkies and fish, pinkies are high in fat and should be primarily used as an occasional treat, once every 4-6 weeks at the most. if your frog is not large enough to take fuzzy, hopper or small adult mice, then i would hold off until he/she is large enough. fish are also more of a treat food then a dietary staple and should be fed as so, such as once every 2-3 weeks. crickets, grasshoppers, mealworms, earthworms, cockroaches, etc. should consist of your frogs main diet until he/she is large enough to move onto larger mice than pinkies, and should be fed even after mice make up the staple of the diet.
In case you planned to ask at another time:
as for heat, i do not recommend heat lamps for frogs, but rather under the tank heaters, just make sure that the frog cannot touch the glass directly where the heater is located, for this area can be warm enough to burn, if you don't have a false bottom style tank put down some landscaping fabric or other heat resistant non toxic barrier to keep the frog away from direct contact. if this is too much and you would prefer to use a light, get a 25 watt or smaller flood bulb and keep it at least 6" above your frog, AT LEAST 6 INCHES!! 40 watt can be used if it is a flood and kept 10" or higher or spot and kept 12" or higher. UV lighting should be provided for your pacman as well as for your plants, just because an animal lives on the forest floor, which not all species live under the canopy, (many can be found in pools or inlets from rivers in tropical savannahs), doesn't mean it doesn't get light or need light in the wild or in captivity. a flourscent blub, like a repti-glo 5.0 would be sufficient.
hope this answers your questions and then some, feel free to ask more and you should get responsible answer in return from most people.
