Backyard Aquaponics
A place to discuss aquaponics

Please check out these close up pictures of my Tilapia from today:
https://imgur.com/a/KHlhC

New fish to a new tank 2 - 3 weeks old in cycle. It is in an inner city elementary school; and school recently started. Fish came pale white now most are darkening. Eye color is changing I just noticed. They are eating and fairly actively swimming around, more than when we first got them.

Plants are growing, I can assume nitrates are being created, however API 5 in 1 Aquarium Test Strips are reading Am. around 0.75 ppm and Nitrites are going up to 3.0 ppm as well.

I salted the tank 5 TBSP for a 250 gallon tank 5 days ago in preparation for the Nitrite spike and have been buffering with Seachem Netural regulator, a Phosphorous based buffer that is supposed to help with Amm. and nitrite toxicity. Today I put in 2 teaspoons along with a 5 gallon top off.

Should I start doing some 25% water changes - that would be over 50 gallons! (I think I overfed the past 3 days, really not much food at all considering their size, but still feel like it was too much)

What are your recommendations? More salt, PWC? I know I need to reduce reduce feeding, like to ever 2nd day or 3rd day. The dark color ones seem more aggressive and nip/ suck at the white ones. Is the color relating to stress, mating, or maybe they are trying to coat their gills by stealing slime coat from the white ones? I don't know. Any shared experience or knowledge would be much appreciated. Thank you!

It is much easier for the readers if you just upload the photos as attachments. Anywhoo... The tilapia look normal to me. The only thing you need to add to your system is patience. 3ppm for nitrites is well within the tolerance level for tilapia. I will say, ditch the strips, and get the bottled reagents instead. They are more reliable.

Thanks for the reply Ronmaggi, patience definitely helped. I think our API reagents test kit was getting about the same reading. It was high Nitrites (max 3.0+) , and Am. Its in an elementary school. Didn't feed them on Friday nor over the weekend. The temperature dropped this weekend and I didn't heat it. Today the water was a hair under 60F down about 10F from before. The water tested lower on Am. and virtually no Ni. Fish went from 3/4ths darkened (eyes rings and scale colors) at their worst to much more pale like their original complexion. Their eyes have much more clarity. Less gaspy. I think the combination of warm water and high nitrite was giving them some brown blood and now that the water is cooler and the biofiltration growbed has had time to catch up and process the toxic nutrients they seem to be living an easier life . Let me know if you guys have any thoughts, Thanks!

The darkening has returned with vengeance! I am starting to think that it is diurnal pH swings (maybe due to algae) combined with Am. stress because our Nitrites are reading 0.. edit: or it could be not enough DO. The water was up warmer again today.

I think you need to take a deep breath and a step back,

Tilapia are quote robust and hardy, they can tolerate more than most species of fish in the aquaponic world by all means continue to test and monitor your system and record your observations but beware of intervening to much as many fish have been killed off through the best of intentions (killed with kindness) by trying to alter there environment to much, have done it myself.

maybe do some research on there tolerance's for water quality and temperature, being a new system it will take some time to settle down so try not to do to much to soon and be patient.

some information on your system build will help, eg growing medium, tank and grow bed material etc.

changes in colour can be signs of stress and they could be signs of other things, stress can be caused by bright light, people constantly looking into the tank or by an aggressive tank mate so observation is key.

good luck

Do you have any reason to believe that the darkening is actually a problem?

Some fish when not exposed to much or any UV light will be quite pale. When exposed to light again they will colour up, some fish when exposed to a lot of light will turn quite dark.

Could it just be a change in the amount of light?