Flies on top of my aquarium/ needlefish question

Question
Hi,
i have a 30 gallon tank with a 3in pangasius catfish, 3.5in
whitetipped shark, 4 in. black ghost knife and a 5in needle fish,

i've had this aquarium for about 3 months and i've already faced
the early mistakes of beginners my fish overcame ick septicimia
and dropsey ( one bala died fromdropsey) and i've learned to
monitor my water carefully. though all i know for sure now is
that my ammonia is at .23 light yellow green
my latest question concerns my needlefish, he seems to have a
frayed tail but no signs of black or red spots so im not sure if it
is tail rot but his tail is a little white and frayed a little bit, he
might be getting bullied but i don't expect this from a needle
fish so i don't know, and on top of that there seems to be little
flies hanging out at the top of my aquarium but i think i might
be overfeeding the fish, but its kind of hard when the white
tipped and pangasius eat so much that im afraid my black ghost
isn't getting enough food so i feed more ( the needle fish eats
feeder fish that i maintain in a quarantined tank) i was
wondering what i should do about my needlefish and aquarium
flies and if i need medicatio, i want to know what ones would be
safe for my black ghost and whitetipped?
thanks alot,
santiago

Answer
Hi Santiago;

I don't think your fish need medication but they do need some water changes and a bigger tank. Replace 25% of the water and vacuum the gravel right away. Do it again in two more days. Keep measuring the ammonia levels to be sure they go down and stay down. Since it sounds like you have been overfeeding to get food to the knife, keep vacuuming at least once a week until the gravel is clean again. Once the crisis is over just make a 25% water change every week and vacuum the gravel every 2 to 3 weeks. This is a good regular maintenance schedule for any tank.

To help the knife get more food, feed him after the lights are out. Ghost Knife fish are nocturnal. You can also use a turkey baster to get food directly to him. Do it very slowly so he doesn't spook. (no pun intended **grin**)

A 30 gallon tank is not nearly large enough for these guys. In the next few months you will need at least a 55 gallon. Here's why;

Ghost Knife fish grow to be over 18 inches long;
http://www.fishprofiles.com/files/profiles/387.htm

Pangasius Cats grow to be over 4 feet long;
http://www.fishprofiles.com/files/profiles/318.htm

Whitetip Sharks grow to be over a foot long;
http://www.fishprofiles.com/files/profiles/328.htm

Needlenose Gar (needle fish) grow to be about 8 inches long and need some salt in their water. It would be fine for the other fish to add 1/2 teaspoon per gallon. Needles are also a schooling fish so they need more of their own to pal around with.

The flies are probably just some opportunistic bug eating whatever they can find on the top. I've had such creatures around my tanks before too. I usually just wipe around the tank rim and edges more and they go away.

Good luck with all those guys.......

At Your Service;
Chris Robbins