Last week Minerva was fine. He (boy beta with a girl name

) has been fine for a full year. And the filtered 5 gallon tank always tests perfectly for amonia and nitrates/nitrites, so we were taking the "leave well enough alone" method - but we can certainly "step up" our water changes = changing more, more often.
There was no problem at all until finding him stuck on the filter intake. We think he had to be sick to get stuck there - and then after taking him off he lay on the bottom of the tank in an arch.
What do you mean by "Stuff the filter"?
Also we have noticed today that he is arching his back and seems to have real trouble swimming. He can "scoot" around but swimming isn't happening. Should we try the epsom salt treatment? Thanks for any feedback/help
I can move the tetra out - but again - for 12 months all have cohabited happily- and the tetra's seem healthy and good right now.