As what others have said, possible reasons are too hot, too little oxygen and different/poor quality water.
Too hot: If you don't already have one, get an aquarium thermometer to stick to the inner glass, submerged about 2/3 from the tank bottom. Digital ones are much easier to read. It's important to monitor aquarium temp constantly. Goldies are cold water fish most comfortable in about 50-77F range. Cold water fish need more oxygen than warm water tropicals & warmer the water the less its ability to hold oxygen. It gets serious if fish resort to gasping for air at water surface. Water at the filter outlet will be more oxygenated than rest of the tank. Your current ambient temp is way too hot for even most tropicals.
- removing top flaps allow for more air circulation which reduces heat from the lights & allows more evaporation to cool the water. Though more risk of dust getting on water surface & not advisable for jumpy fish.
- ice bags or ice packs are very temporary solution & melt too fast to be efficient. Seal well in ziplock bags to prevent leakage if placing directly in tank. Similar alternative is freezing partially filled 1.5 or 2 liter plastic soda bottles.
- Unless you have lots of moolah to burn, aquarium chillers are overkill for freshwater tanks. The best effective cheap method is to use clip-on small fans angled across the water surface. This increases the evaporation rate which in turn cools the water by about average 5-7F, but you'll need to top up the water level more frequently. Fans sold by fish shops are generally adapted from computer case fans, you can even DIY your own at fraction of price. Many consume less than 1W of power, very cost effective.
Too little oxygen: More air stones is ok but note the bubbles themselves don't contribute to oxygen levels, it's the surface agitation that matters. Several airstones placed at different locations can be 'powered' using a single air pump by use of those multi connectors. Those long airstones can provide a wall of bubbles in the background, quite effective. Alternative is using a rain bar for the filter outlet, suspended above the water surface it agitates the water well.
Water quality - advisable for fish owners to buy water testing kits, even those all-in-one strips are better than nothing. Important to periodically test pH, nitrite, nitrate, ammonia. Test pH of your new water supply direct from tap before use in the tank, it could be very different from your previous area. Fish can generally tolerate only a 0.5 swing within 24 hours, remember pH is logarithmic (10 times effect of previous pH). There are natural methods to fine tune pH if too out of whack. Use something like Seachem Prime to condition & detox tap water before use. Do regular water changes, up to 25% every 1-2 weeks. Note goldfish & most catfish are champion poopers, so water changes & good filter are a must. Having a permanent bag of biological media (sintered glass, ceramic rings etc) in the filter helps improve biological filtration to tackle toxic nitrogenous compounds. You can also have some tough live plants, not soft leaved ones that goldfish will eat, may need to be planted in pots to prevent uprooting. Live plants help with oxygenating water & also removing some toxins as fertilisers.