i have an issue in that one of my cherry barbs is flashing occasionally, but does it a lot after feeding. The usual stuff: Tank 18 US gal with a fluval U2 filter only ive removed the carbon and stuffed plenty of filter floss in its place Temp 25 deg. Centigrade Ammonia, nitrite nil Nitrate usually around 20 by the time of water change Weekly 25% water changes with RO water with minerals which have been exactly the same for the past 8 months Inhabitants: 5 cherry barbs (i know its not enough but thats another story), 6 sterbai cories and 2 assassin snails. Ok storytime. The tank has been running for 8 months 2-3 2weeks ago i had a couple of cherry barbs die which i did not see coming. I thought id check my pH and it was over 8 (source is 7.2 after leaving to stand for 24 hours with an air stone in it). Turns out i have had some limestone in the tank since day 1.. Oops.. So i removed that rock. Steadily seeing my pH lower with every water change. 7 days ago i added an XL indian almond leaF to my tank and i plan on continuing to use IALs. About 5 days ago i started seeing a few cherry barbs flash so i started worrying. I bought some fluke solve which i havent used yet. I did a massive water change and now they seem much happier - i think my issue is that i was still feeding them as if i had 7 adult cherry barbs rather than 5, so i saw an increase in nitrates. 4 of the 5 havent flashed over the past 2 days. One of the cherry barbs still flashes numerous times in short succession but only after i feed them. Theres no clamped fins, appetite is as big as ever, and theyre all still behaving like the barbs they are... No signs of lethargy.. If i didnt have my cories id have just begun a 2 weeks treatment of fluke solve, but id rather not do it unless i really have to. What would you guys do? Im going to do 3 50% water changes over the course of the week. Is flashing after feeding a thing?