My jack dempseys were not breeding, so i figured they needed a spark to get them to breed. I taped a big mirror the size of the tank to the front of the tank and now they are all excited trying to attack themselves in the mirror. Ive seen this on youtube, and the person was successful at getting their jack dempseys to breed with this technique. I was just wondering how long i should keep the mirror up for? It looks like its working very well so far. I have had the mirror up for 30 mins and they are going crazy at it and the female has her breeding tube out now! Any info on how long to keep the mirror up would be awesome. Thanks!