Brown algae and dead fish

[Newbi]

Hi all brand new to the forums and new to aquariums I got my wife a 37 Gallon tank for Christmas and this morning she left for work every thing seemed fine 2 hrs later our son woke up and there was brown algae covering all of the ornaments and 3 fish were dead we had no issues up till today about 3 days ago we introduced 5 tetras into the tank not sure if the brought ick in or what but our gourami and some of the guppies seem to have like crystals on their fins any help would be appreciated

 

[dcutl002]

Welcome to Aquarium Advice! There is a lot going on here with this tank.
For the possible ICH: can you get a picture of the fish so that someone can diagnose if that is what they have?
Can you tell us what your Ammonia, Nitrite, and Nitrate levels are?

That will be a good start.

Don

 

[coralbandit]

The brown algae is likely diatoms which will go away in time on their own..Are you able to test your water parameters?
Have you changed water? Tanks need regular water changes to remove nutrients and new tanks demand more water changes often until the tank itself is 'cycled' and the filter /bacteria can convert ammonia and nitrite to the much less harmful nitrate....
The nitrates need to be reduced by water changes...
Any amount of ammonia or nitrite exposure over a period of time will kill fish pretty quick..