There are two easier ways I can think of, others may have more.
1 Keep one jar empty and have a bucket of clean water. Fill empty with clean water, tip one jar and fish into net, put fish in clean jar, clean jar and fill with clean water and repeat.
2 When I was breeding them I had tanks that were 600mm x 600mm. I made tanks that were slightly smaller with stainless steel mesh on the bottom and divided into compartments about 75mm square. put a male in each one and excess food drops out the bottom and can be siphoned off. To do a water change lift the internal tank 3/4 of the way up and drop again. I had glass straps that they rested on so the internal tanks were off the bottom.