General PH levels

Hey all.

So my (tank bred) discus are in a 55 that until the last few days was hanging out around 7.1 PH. The smallest in the group was a little sluggish, so I've lowered it to about 6.8-6.9 and I'll probably go a wee bit lower. He seems to be doing much better now, actually, although it could truly be a coincidence.

My question is, can anyone lay out the best PH levels for various activities? Like, breeding, raising fry, what causes aggression, etc?

I won't likely be breeding soon but it seems good to know.

to raise fry, as close to neutral (7.0) would be better from what I have learnt over the years.

The 'ideal' pH is a lot less important than a stable pH.

These fish of ours have been bred in water around 7 for many generations now. If you had wild caught fish, you would want the pH around 6 or maybe 6.3, but for our tank raised specimens, anything around 7 would be fine. For breeding I like the water to be around 6.7 just because the eggs seem to fungus less in the slightly more acid water, and the chance of fertilization is higher.

For raising fry, I will bring the pH up to 7.2 or even higher, with an increase in the hardness of the water to aid in the development of strong bones.

Stability is the key. Keep the pH stable, and the fish will be happy.