my danios are loosing color (Fading) after four years, possible health issue or just old age?

Question

Hi, about 4 years ago I bought five small, short-finned zebra danio to keep in a 10 gallon tank. 3 years ago (a year after I bought them), I left on vacation for 2 months and while I was gone my friend watched the tank for me. By the time I got back two of the danio had died and one was sick, I don't know what they had. The third danio died directly after I had returned from vacation, leaving me with only two zebra danios. About 6 months later a different friend decided she did not want her two fancy male guppies any more so I told her I would take them for her. I put them in the tank with my two remaining zebra danios and all seemed fine.
Now, it is 4 years since I bought the danios, 3 years since half of them died, and 2 years 6 months since I added the guppies to the tank.
The tank has always had a heater, filter, and bubbler.
I check the ph levels every week when I replace 25% of the water. And I clean the filter every month.
The fish are fed TetraFin Tropical Flakes once a day.

The reason I worry is because in the past two weeks their coloring has faded, now you can barely see their stripes and many people confuse them for pearl danios although they are zebras and their stripes used to be so bright.
I realize they are old, and that most danios only live to be about five years old, however I'm very attached and was wondering if there was anything I could do for them?
At first I thought it might be a vitamin deficiency so I started giving them brine shrimp and betta pellets once a week instead of their regular flakes (I thought a variation in their diet might help), but that has not helped.
I have already checked the temperature and ph levels to no avail, they are both as they've always been, within the normal range.

Answer 1

yeah danios and lots of other fish fade with old age.poor things dont usually last long after that so be prepared for bad news.sorry.

Answer 2

Check to make sure the temperature isn't too high. Danios are coldwater fish (though they are fine in tropical water). If it is more than 78*, that is probably the reason for the fading. Keep your tank around 76* (that temperature is perfect for Guppies as well) and you should soon see your Danios back to a normal temperature.

Another reason would be from newly introduced stress... Have you added anything recently? Have you changed anything in the tank? Has the tank moved to a different location? These are all stressful to fish and can lead to temporary loss of coloration. Email me if you have any questions.

Soop Nazi

Answer 3

1. I was thinking maybe a malnutrition and was going to suggest switching diets but since you already did that i will say....
2. Try flakes that will bring out color in your fish they will say on the title whether or not they bring out their colors.
3. If this doesnt work than it must be old age.. :[ Its a sad thing but at least they had a great owner to take care of them!

- Good luck! If you need anything you can email me! :] -

Answer 4

It is possible the guppies brought in something the danios were not immune to. Your tank and bio-load are right and you are doing all the right things for a tank. Maybe change your food out a little more, it tends to make them sick if its old. Two months is maximum shelf life in my opinion. I think it gets loaded with bacteria after a while causing fish to become floaters from gas in the gut.

Answer 5

im so sorry but in fact they are dying, i know your attached but you will all laugh at me for this i burry my fish in my little fish cemetary it helps afterwards to get some styrofoam and with a tooth pick etch in their names and cover it with very loose hobby cement i then stick 2 toothpicks up the crave stone and plant it in the ground like a tombstone i know its sad but this will at least help you move on... im so sorry for your loss.