Confirmation if this can work

[Xenoblade]

My friend is setting up a 40 gallon, but I’m pretty sure he used ChatGPT. I’m not the most knowledgeable with nano salts, so I’m not sure if this works.

He wants to do a carpenter flasher wrasse, longfin fairy wrasse, starry blenny, yasha goby, lagoon shrimp goby, hectors goby, 2 pistol shrimps, a mandarin goby, and an Ocellaris clown.

He says he’ll put the 2 pairable gobies on opposite ends of the tank. I’m just not sure if this will work in a 40, as it seems like a lot. Especially since he wants to stock up and have a bunch of shrimp and crabs too.

 

[ThisIsTheWay]

I don't have personal experience with 2 pistol shrimp at once, but based on a bit of research I think it'd be ok to do 2 of the same pistol shrimp in a tank that size. If you get lucky they may pair up.
Inverts aren't really considered to add much bioload to a tank, I have an extensive list of inverts in my 25gal AIO and everyone gets along fine. The main thing is to go slow and make sure your tank is mature enough to handle lots of scavengers and grazers.

My concern with the plan is more aggression and food competition.
On the aggression side, clowns can get aggressive as they get older and if I recall correctly starry blennys can be really bad bullies too once they mature. I'll let other people chime in as well but you probably want to skip the starry blenny.

On the food competition side. Mandarins and wrasses both do best with a good supply of live food (copepods, amphipods, isopods, etc.). If you can get a mandarin that will eat frozen that will help a lot, but all 3 of those fish will still be in competition with one another and will probably strip the copepod and amphipod populations down rapidly. Ideally you'd run a refugium to help resupply the display but even so you may still need to dose additional copepods to the tank. I personally probably wouldn't add the mandarin until I was sure the tank was mature and full of live food.

 

[Naekuh]

Crabs eat fish... even the ones you think are safe.
Some of those wrases like deep sand beds.
All of those wrases are known jumpers and love to commit seppuku on your carpet when your not looking, or even manage to jump though holes in your net and end up on top of the net to become a treat for your cat if you have one.

Yasha Goby and Pistol Shrimp combo is NOT beginner friendly.
Mating Pair is not gaurentee'd if you put a female + male, unless it was sold as a mated pair.

Mandrian goby is almost impossible to keep unless its been trained to eat dry/frozen food, and even then with the wrasses as competition, it probably wont get any and will die of starvation, or your friend will pollute the tank trying to feed it by over feeding the tank. You need like sump with a refugium stocked with copods, or a very well established tank for them.

In short, i have only met 1 person in my entire life who had a starter fish as a mandrain, and ended up not killing it, because she got so lucky that it took to mysis on the first day, and it was the ONLY fish in the small 10G AIO.

I know people like this... if they are commited, you can't do much but call the Tang Police on them.
But on a serious note, tell him how difficult the mandarin is... then tell him the YASHA is also very tough. Have him watch some videos from the inappropreate reefer on Youtube, and his drama with the Yasha... i dont think he even has one.