fish shape??? (continued)

Question
QUESTION: it made me start a new question. said there were to many follow ups..i've been telling you about my tank for a couple days now...

so i was wondering what i should do then to prevent the rest of my fish from getting sick... i've increased water changes and am going to take a sample to a pet store later this evening as well as to get them some different food... but is there any particular medication i should use on my overall tank? quick cure? maracyn-two? diatom filter? you had mentioned treating for an intestinal infection? thus far none of my other fish appear sick... but since i lost two so close to each other i am kind of worried...

by the way... thanks for all your help

ANSWER: I don't know why the computer system here does that to people... It happens a lot.  At this point I would not medicate them because we don't know what we are medicating for.... Let me know what the water chemistry tests are when you get them back.  You can add aquarium salt for now... and I try to add a varied diet to all of my fish.  I feed them twice per day... flake food (switch brands often) in the morning and then in the evening I feed them flake food and other food such as brine shrimp and tubiflex worms. I also supplement everyone's diet with sinking algae wafers three times per week.  You can add trace elements (product) to the tank too and this time a pieces of zucchini wedges.  Don't let it sit in your tank for more then a couple of hours or it will foul the water.  dave

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

QUESTION: ok so here are the water chemistry results:

AMMONIA: 0.5mg/L (i know the normal range is 0.0-0.25 but couldn't it just be high since i had fish die?)

NITRITE:0mg/L

NITRATE:0mg/L

pH:7.0

ALKALINITY: 40mg/L ( i know normal range is 80-300mg/L so should i add more Novaqua+ which is supposed to be my buffer?)

HARDNESS:150mg/L

CHLORINE AND CHLORAMINE: 0mg/L

SALINITY: the guy at the pet store had no way of testing this one but i can tell u that with every usual weekly water change i add about one rounded tablespoonful of aquarium salt since its a ten-gallon tank and i change about 50% per week..

TEMPERATURE:80-81 degrees fahrenheit ( i know this is kind of high but i'm not sure how to change it since thats the normal temperature of my house...)

i was also wondering if you thought it was a good idea to change my filter cartridge out or if thats to much change... i usually change it out every 1-2months but this will have been a little less than one month...
its a Topfin filter if that means anything... the tank they are eventually going to be moved into is a 20-gallon eclipse tank...  

Answer
I would definitely change the filter media on a monthly basis. Active carbon stops absorbing after about a month of use.  I would also cut back on the salt to about half of what you are using.  Everything else seems to be ok except the ammonia which is only slightly elevated.  How are the rest of the fish doing???? if they are not sick at this point then I doubt that they are going to get sick.  Let me know... dave