Hey everyone,

I have 5 adfs in a 20 litre tank and have had them about a year. They used to sing like mad, but don't any more and I miss it so thought I'd post here and check if I'm doing anything wrong. There's 2 females and 3 males (used to be a 3rd female but she escaped a few months back and couldn't find her til it was too late :'( )
They used to sing ALL the time, and be constantly mating. For the last 3 or 4 months they virtually never sing bar the odd croak, and mate far less frequently. Also, there's never been any eggs produced. They're in 26° water, same as always, fed on a varied mixture of fish flakes, frozen brine shrimp/bloodworm/daphnia and occasional live brine shrimp. Same tank. Same location. Partial water change every 2 weeks.
Anyone have any ideas? Or even just general suggestions to make them as happy as possible?