I guess the longest would be my newbies - 2 Golden Puffers (Auriglobus modestus) that are about 3 inches and growing.....chubbiest would have to be my female Emerald puffer (Tetraodon cutcutia) "Chubbs"...while only about 2 inches long, she is probably 3 inches around
All of my dwarves are about half an inch long. Its funny watching them swim up along my pleco who is 4 times their size and you can tell they're considering nipping it. But then they think better of it and swim away.