Angel Fish Keep Dying

Question
QUESTION: I have a 30 gallon aquarium (Water levels test normal.)with 2 small angelfish, a couple of balloon mollies, and a couple of diamond tetras, and two cat fish.  

Last week, the pump on one of my other tanks broke. It is a specialty pump for a hexagon tank, that had to be reordered. Since the ammonia level in that tank was rising, I had to temporarily add those fish into my 30 gallon tank.

The fish I added to the 30 gallon were 2 guppy's, 2 neons, and 2 lyre tail mollies.

The next morning, one of my angels was dead. I didn't see any sign of injury, so I didn't think much about it. Went out and bought another angel, the next morning, that one was dead.

I got another angel. A few hours after putting the angel in the tank, we found the other fish going at the angel. (Nipping, etc.) The angel is obviously injured. I removed it from the tank. Hopefully it will be ok.

I never had any problem until I added the fish from my broken down tank. We noticed that all of the fish except for the angels have formed a "school" they stick together and chase each other all over like crazy.
The also do seem to be play nipping at each other at times. Even though they stick together.

I don't know what to do. I have had fish "play nip" in the past, but it has never resulted in fish dying like this.

So basically, I need help with this agression issue. Thank you so much!! I really don't know what to do. I have never had this problem before.



ANSWER: Hello,
You have two problems here.  The first one is Mollies, and Angel fish do not mix.  The reason being that mollies need alkaline water, and Angels acidic to normal.  The mollies will nip the Angels, causing stress, and when they are small they will die.  The second problem is adding too many fish at a time in a tank will change your water chemistry.  You ammonia level must have gone up.  When ammonia levels go up, it will harm fish, and could have killed all of your fish.  
Also make sure that you have enough water movement in your tank so that they have oxygen.  Maybe an air stone would help.  It isn't normal for all these fish to stick together.  Check your PH, ammonia, and nitrate levels.  Do a water change.  This is all I can see is happening.  When the PH level is not right for one fish, and right for another, things go wrong.  You must always read up on fish, and their needs before you buy them.  The pet store vendors will tell you all fish get along, and this is so untrue, but they are there to make money.  Be careful on what fish you mix in with Angel Fish, there long fins are an attraction to most fish.  Mollies, and Angels certainly don't mix.
Hope this helps
Lynda

---------- FOLLOW-UP ----------

QUESTION: Hello, Thank you so much for your reply! I have been keeping a good eye on the levels in the tank when I had to add all those other fish at once. The ammonia level did go up slightly, I added Ammonia-Lock to treat that. Since then, it has been in a normal range. PH, nitrates, etc, are all in the normal range. We also have a good air stone.

Since Mollies don't mix with Angels, I think I will put the Mollies into the other tank.

Do you think that would stop the aggression?

The remaining ones would be the Angels, 2 neon tetras, 2 diamond tetras, 2 guppies, and the cat fish.

Can those be mixed? Also, will the other fish stop nipping once the mollies are out? None of them ever nipped before.
Thank you so much!  

Answer
Hello,
It would be a good idea to put the mollies in another tank.  Mollies need alkaline water which is easy to do by adding crushed coral to your filter.  Bring the PH up to 8.0  - do this slowly depending on your PH at the moment.  They also like salt, so adding 1 teaspoon of diluted aquarium salt would help them.  If you decide to keep an "only" molly tank, you could add more salt.  Two females to a male is best.
Angels, neon tetras, and diamond tetras do well.  Guppies are quite peaceful too, and are usually nipped by other fish.  Keep them 2 females one male is best.  Later on you could add more neon tetras, and diamond tetras.  They are schooling fish, and love to be kept in groups of 5-6.
Hope all goes well.
Lynda

I just want to add that when schooling fish are kept in groups of 5 or 6 they stay together, and chase each other keeping their mind off any other fish in the tank.  The Tetras fish you have are peaceful, and should be kept in groups.