With about 45 current members, the Tropical Fish Club of Burlington has been uniting freshwater fish fans for almost a quarter century. Judging by the scene in the club house, it’s a small but spirited society. Some 40 people attended the event, which was emceed by Doug Patac and featured everything from fish to filters to cartoonish figurines of nude females — for aquariums, of course. Around the meeting room, several long tables were loaded with fish and plants in clear plastic bags of various sizes. While local vendors donated some of the auction items, most were fish bred by the hobbyists themselves.