I am attempting to control mobs from multiple creature mods to create a unique world. Whenever I try and add a mob to an underwater spawn though nothing appears.

This is my current code....
potentialspawn.json
[ { "mob": "mocreatures:anchovy", "block": "minecraft:water", "weight": 5, "groupcountmin": 2, "groupcountmax": 4 } ]

spawn.json
[ { "mob": "mocreatures:anchovy", "biome": ["minecraft:ocean", "minecraft:deep_ocean", "biomesoplenty:coral_reef", "biomesoplenty:kelp_forest"], "result": "allow" } ]

Is there something glaringly obvious I am missing here lol?

Mocreatures mobs don't work well with In Control. People have struggled with this before and I'm not sure how to solve it or if I can do anything about it.
It might help to get rid of CMS though (Custom Mod Spawner). Contrary to what MoCreatures makes you think you don't actually need that mod

I've removed the CMS already, and I have started to get things to work well. Just having issues with mob counts now. Either everything is extremely sparce (which is a goal, just maybe a little less sparce would be nice, lol), or I get things completely overcrowding the world.

Try the latest version which was released today. It has a much improved mob counting system

Well, not sure if I am messing things up and that is why it is seeming to work or not, lol, but it is. Whatever you fixed has been helping control the mob levels a bit, at least for my beach spawns.

I'm using the following to achieve what I want....

Spawn.json

[
{
"mob": "mocreatures:crab",
"biome": ["Beach", "Gravel Beach", "White Beach"],
"result": "allow"
},
{
"biome": "Beach",
"mincount": {
"amount": 20,
"perchunk": true
},
"result": "deny"
},
{
"result": "deny"
}
]

PotentialSpawn.json

[
{
"mob": "mocreatures:crab",
"weight": 5,
"groupcountmin": 2,
"groupcountmax": 4
}
]

I'm still learning this whole system (and json at the same time) but suprisingly it's doing it's job. Thank you for the wonderful mod!