A great thread here. A lot to learn and discuss.

Crappie and YP are similar in several respects and are direct competitors with each other. They spawn about the same time with the YP just before the crappie. The yoy of both will not eat each other but the adults of both will eat the yoy of the other.

Crappie - Spawning occurs from about 59 degrees Fahrenheit to 68 degrees Fahrenheit ( 15-20 C )

YP
Reproductive Habits:
· Mature at ages 1-3
· Spawning occurs around late winter to early summer in water 2-18.6°C
· Occurs at night over vegetation and sandy or rocky bottoms
· Eggs produced in a gelatinous, accordion-like ribbon
· Fecundity is about 2,000-157,600 eggs per female

The yellow perch has the capability to influence recruitment of black crappie (Pope et al. ...
At least two potential avenues for yellow perch influence exist: competition for food
resources and direct predation by perch on the other panfish species. ...

As noted the yoy will compete for forage and the adults will also compete for food.

Both have a history of over populating leading to stunted populations. Both do better (bigger and better condition)in the presence of heavy apex predation (LMB , Esox , WE etc.).

One advantage to YP is the ability to eat pelleted feed easily.

Some good results have been shown in ponds using HSB , crappie , TFS and FH. You could likely halve the #s of crappie used in that plan and replace them with YP. Might get some interesting results.