Skunk Shrimp

I'm new to this site and other than my hello post, this is my first one.
I've had 2 shrimp in my 20 gallon tank for over 5 months. 1 Peppermint and 1 Skunk Shrimp (who was really friendly and would eat almost from your hand), anyway, they both died within a week of each other.
I didn't realize they needed iodine supplements to the tank, but they were both eating flake and mysis shrimp readily.
I want to replace the Skunk Shrimp, but I'm not sure if I did something to them.
Any ideas or help out there would be greatly appreciated

 

skunks are cool lil guys. they need iodine for sure (all inverts do - snails, corals, shrimp) however too much isnt good for the fish.
and like all inverts copper and nitrates are highly toxic to these guys.
make sure you test for that.
peppermints are scavangers so they eat anything left overs and i have found mine grazing on algae as well.
zooplankton is important for them to have as well. or other food ment for inverts. there is tons out there.
normally you leave them be and they take care of themselves, eat whatever the fish dont.
one way to tell they are healthy is the shedding of their old coat. iodine helps them with this. but be careful cause it can resault in early sheding as well.

 

Thanks for the response. I'm doing a water change today and will check for nitrate and copper levels. My skunk had been molting once a month and I could always tell when he was getting ready to molt as he would hang on the side of the rock and not really want to eat. The Peppermint hid under a rock all the time except to come out and eat and he never molted once that I knew of.
I will also add some iodine, stablize the tank and try again. I have another Skunk shrimp in our big tank (90 gal) so I don't want to lose him too.
They are really cool.
Thanks again.

 

peppermint (so i have read) are nocternal so its not odd when you dont see them during the day.
make sure to check for ammonia and nitrite as well. this is very important. calcum and kh. salinity should be above 1.023 for inverts too.