cleanup?

Question
Hello.
I am new to the aquarium world.
I have a 55 gallon freshwater tank with 25 fishes (Platys, glo fishes, tetras & guppy.
I test the water every 2 days and it is generally good quality. We also have about 10 new baby fishes.

However, I notice a lot of sludge. So I decided to take every ornament from the tank (we have a castle, a boat and a lot of plants) and do a thorough cleanup.

After that, I notice both the platy's and mollys are always at the bottom of the water, not swimming. If you check, they are alive. but is this normal?
Thank you for any help you can provide.

Answer
Hi Roni,
It sounds like you made the tank crash.  Normally if you do a gravel vacuum, you only want to vacuum half of one side of a tank, and do the other half on your next clean up.  The reason is because the floor contains a ton of beneficial bacteria that is necessary to break down the toxins in the tank, if you clean thoroughly, you will suck all this up.  Then tank now cannot handle the fish's bioload.  

When you said plants, I dont know if they are live or fake, but if you have a densely planted tank, you dont do any gravel vacuums because the mulm (sludge), is what feeds and fertilizes the plants.  

I would do a 50% water change right now.  And test the water.  It might sound like they have ammonia intoxication, but I may be wrong.  Check to see if they have difficulty breathing.  Fast breathing and inflamed red gills are signs of ammonia intoxication.
-Matt-