Heaters for jack dempseys?

ive got 8 JDs in my 75 and ive had alot in my time ive never had a problem with heaters

I've got 2 jack dempseys in a tank with 2 oscars and found a broken heater a while back. Don't know who did it, but if you are concerned, look into getting a stainless steel or titanium heater. You can get them around the same price as a good glass heater. You can also place your heaters laying down in the back of your tank instead of placing them vertical. They will have a lesser chance of being messed with this way, and you won't see them sticking on the back of your tank.