My bottom feeders keep dying

[billsfan]

Why do my fish keep dying? Hi all, I have bought multiple types of bottom feeders and they all die.
My tank:
15 gallons
1 betta fish
4 corydoras catfish : white/clear (3 died, 1 remains)
8 neon tetras (1 died, 7 remain)
2 snails (2 died, 0 remain)
5 Cory catfish: spotted (5 died, 0 remain)
1 blue ram cichlid

2 weeks after getting my betta, I introduced the 4 white catfish. Within 2 weeks 3 of the four had died. I then got 8 tetras and they were all fine. 2 weeks later I added 2 snails in hopes that they would survive, however they died within a few days. I then purchased 5 spotted catfish and the blue ram cichlid yesterday. Two of the catfish the day I purchased them, along with one of my tetras, and the other three died today. What is happening to cause all of the bottom feeders to die?

 

[NoodleCats]

Corydoras are sensitive to ammonia spikes which are common after adding new fish.

Couple things though...
All of these fish need a 20 gallon or larger, except the betta... and bettas and rams is a very dangerous mix as both species can be really territorial when they feel like it.

 

[FreshyFresh]

Welcome to the site and hopefully you enjoy your stay..

Questions for you..

How long has the tank been set up?

Do you have a test kit that allows you to read ammonia, nitrite and nitrate in PPM? If so, what are your readings in PPM.

How often do you do water changes and how much water do you change each time? (hopefully it's weekly and you change 50-60% at a MINIMUM)

Provided all that is OK, what are you feeding the cory cats? They have different feeding needs than the other fish you list. You need to feed corys quality sinking pellet foods, blanched veggies, etc. If you think the flake food you sprinkle in the tank for the other fish is enough, your corys aren't going to make it.

 

[NoahLikesFish]

Did you do ANY research? What’s your substrate? If you did research you would know rams need very soft water, cories need sand substrate, neon tetras need 20 min they are very active also bettas shouldn’t really have tankmates except for small peaceful schooling fish or shrimp or cories or bristlenose plecos. Also nothing with long fins. Also don’t call corydoryas bottom feeders, they are much more then that and actually need food. They don’t just eat everything off the bottom. They do need sinking food but they don’t just eat algae and poop and waste. I would return everything and read up on the nitrogen cycle and make a nice planted aquarium then get new fish

 

[NoahLikesFish]

How did you kill a snail ?!