why dont my fish get bigger

Question
i dont change the water very often. i feed them mostly flake foos but lately i have begun to give them dried shrimp.-------------------------
Followup To
Question -
hi, i have had my tank two years now. it is a 3 foot tank in which i have kept all kinds of tropical fish from guppys to silver dollars. my problem is that my fish never grow in size and in some cases even shrink. i have tried in vain to find the answer but to no avail- WHY DONT THEY GROW?
Answer -
Hi Ronan;

How often do you make water changes?
How much and what kind of food do you feed them?

Chris Robbins

Answer
Hi Ronan;

You need to make some water changes. Remove 25% of the water once a week and vacuum the gravel at the same time. This will lower the nitrates that are keeping the fish from thriving. It will also stabilize the pH. If pH is too low the fish get thin and can't breed or function normally. All tanks need partial water changes of 25% at least every 2 weeks.

Have the water tested at your local fish store. Ask them to test pH, ammonia, nitrites and nitrates. PH should be 6.8 to 7.2. Ammonia and nitrite should be 'zero'. Nitrate should always be below 40 ppm. Regular partial water changes are the only effective way to normalize these levels if you find them irregular.

Followups welcome

At Your Service;
Chris Robbins