catfish eggs

Question
I have catfish eggs about 4 days old . I have then in a net set up in the same tank as the parents. I have tried this several times and have had no luck. I would like to know what else to do to help them hatch. My parent catfish are about 5 years old and the female lays less and less each time and I figured it is related to her age . Hope you can help me out. My tank is a 20 gallon I use well water and change the water once a month with a clean filter and I change probably 25% of the water. I have 3 glass fish not really sure that is  their real name but you can see through them and 4 zebra fish and 1 beta ,1 algae eater,2 catfish. Hope you can help.,

Answer
Hi Nancy;

You didn't mention what kind of catfish they are. I will assume they are cory cat eggs because cories are commonly kept in community tanks. If they never hatch I would suspect the male is sterile or the eggs are deformed in a way you can't see. Cories breed in groups too so you might get a few more to help them all be successful.

Since you do water changes monthly instead of weekly it may also have something to do with nitrates (NO3). Nitrates build-up over time and can very much affect the ability and willingness to spawn as well as fertility. The only way to remove nitrates is by performing frequent partial water changes. If done weekly along with a gravel vacuuming you can usually keep up with it as it is produced by the bio-system. If done only monthly, they get higher and higher over time. You can buy a test kit for it so you can see what's going on in there. Keep it under 40 ppm for good health in all your fish. So, replace 25% of the water weekly and vacuum the gravel and things may work out better. Here is a web link to information about cory breeding. Maybe something there will help;

http://www.planetcatfish.com/shanesworld/shanesworld.php?article_id=312

Keep in mind that there is another toxin you can test for called nitrite (NO2)and they are commonly confused for each other. Nitrite should be at a level of "zero" in a balanced aquarium. If you see it rise at all it's usually because of New Tank Syndrome, overcleaning, overcrowding and/or overfeeding. Basically, anything that affects the bacteria balance can cause elevations in nitrite.  

Good luck...

At Your Service;
Chris Robbins