I'd bet annectens as well, just because - especially back then - those were the most commonly imported species.
I grew an annectens to about 2' in a 75g...and then moved it to a 100g Rubbermaid stock tank. They're not super-active fish so he seemed healthy and happy in both of these set-ups.
Keeping ANY tank clean can be a challenge with lungs, as they are really messy eaters. I kept just a little gravel in his tank / tub to make seeing and siphoning waste easier... For filtration, I used a pump with a pre-filter to stir up and catch debris...as well as an (air-driven) sponge filter. Mine hung out in big PVC fittings...
Matt