What is the tank size?
Male Endlers are somewhat aggressive,but not to the point to where it becomes The Hunger Games.Depending on your experience,I would say keep about 40-50;with a lot of water changes that is.You could probably sell the rest to a LFS for about fifty...
Figure out the sexes first.If you have the 1:2 ratio,you should be fine.If you don't,with decent filtration and water changes you should be able to add two more of whatever you need.
Poor water quality could've also been a culprit.
He is most likely stressed out.I would imagine you don't have a test kit,If you do,test the water for Ammonia,Nitrite and Nitrates.If you don't,do a 50-75% water change.
Sorry,even if you do have a test kit,do a water change
I would say yes.The same thing happened to me,I got a Mickey Mouse Platy and she gave birth to Mickey Mouses even though there were about 5 other species of Platies in the same tank.Like @Floundering_Around said,if you want to keep the strain,get another one just to be safe.
I would suggest Cory Catfish.They are very peaceful and spend most of their time at the bottom,scavenging for leftover food.They have great personalities and are always energetic.They are shoalers and prefer to be kept in groups of 6+.
Hope this helped!
I was planning on adding Anubias Nana,Java Fern and Water Lettuce to my 10g tank that has a 13watt lightbulb,will this be enough to grow all of the plants?Will they live off the waste from a Betta?
Thanks for any and all help!