If I remember correctly, neons, xrays, and danios are extremely rare to see spawn in an aquarium environment, so I wouldn't put too much effort into trying to make that happen. They are generally bred on fish farms using special horomones, or taken straight from the wild.
If convicts or kribs aren't spawning, there's either something very wrong, or you don't have a male/female pair. Like xOxOxO said, usually you will want to start with 6 or so of each, and let them pair off themselves. You mention having obhtained pairs that had bred before, but often times what you were told may or may not actually be true. If it is true, I'd recommend asking the person you got them from, what they did to get them to breed, because obviously it was working for them.
Onto the help:
Can you be just a bit more specific as to your water parameters? 6.2 - 7.5 is a huge range, and it would be helpful to know specifically which fish are in which kind of water.
What temperature do you keep each type of fish at? If you change the temperature to encourage spawning, what do you change it to?
What is the GH/KH of the water for each type of fish?
What is the tank decor for each type of fish like?
You say you've read everything there is to read about breeding your fish. Can you tell us what you're doing already? Again, for each kind of fish. That may help us find a problem, tweak your method, etc. in order to come up with something that works for you.
No one is purposely keeping "the secret" to breeding from you, it's just that there's no "one size fits all" answer for how to successfully breed all fish, which may be why you feel like no one's letting you in on "the secret". No one can give you that kind of answer because it doesn't exist. Each kind of fish has different "requirements" (I use the term loosely, for there are always exceptions), for what will get them to breed. I have 2 cichlid tanks, one africans, and one central americans, with decor and parameters matched to what they prefer, and they all breed like crazy. My rainbowfish in another tank however, will likely never breed, because it's more difficult due to their specific requirements, which I am unable/unwilling to recreate for them at this time.
The more info you give us about what you're doing now, the more we can help you adjust it so your fish can start turning their tank water into love gravy!
If convicts or kribs aren't spawning, there's either something very wrong, or you don't have a male/female pair. Like xOxOxO said, usually you will want to start with 6 or so of each, and let them pair off themselves. You mention having obhtained pairs that had bred before, but often times what you were told may or may not actually be true. If it is true, I'd recommend asking the person you got them from, what they did to get them to breed, because obviously it was working for them.
Onto the help:
Can you be just a bit more specific as to your water parameters? 6.2 - 7.5 is a huge range, and it would be helpful to know specifically which fish are in which kind of water.
What temperature do you keep each type of fish at? If you change the temperature to encourage spawning, what do you change it to?
What is the GH/KH of the water for each type of fish?
What is the tank decor for each type of fish like?
You say you've read everything there is to read about breeding your fish. Can you tell us what you're doing already? Again, for each kind of fish. That may help us find a problem, tweak your method, etc. in order to come up with something that works for you.
No one is purposely keeping "the secret" to breeding from you, it's just that there's no "one size fits all" answer for how to successfully breed all fish, which may be why you feel like no one's letting you in on "the secret". No one can give you that kind of answer because it doesn't exist. Each kind of fish has different "requirements" (I use the term loosely, for there are always exceptions), for what will get them to breed. I have 2 cichlid tanks, one africans, and one central americans, with decor and parameters matched to what they prefer, and they all breed like crazy. My rainbowfish in another tank however, will likely never breed, because it's more difficult due to their specific requirements, which I am unable/unwilling to recreate for them at this time.
The more info you give us about what you're doing now, the more we can help you adjust it so your fish can start turning their tank water into love gravy!
