Besides Disease What Would Cause Fish To Flash?

Hello all. Sorry lengthy post ahead....I have had an ongoing problem in my tank for well over a year now. It's a 20 long dirted heavily planted tank. Params have been stable for a long time at ph 8, 0 nitrite, 0 ammonia, 5 nitrate. I forget the exact hardness reading but I have pretty hard water. For over a year every single one of my fish (harlequin rasboras, peacock gudgeons, dwaf gourami, and peppered corys) flash fairly frequently. The rasboras very rarely do it and my peacock gudgeons and corys seem to be the most effected if that means anything. I have had difficulties keeping corys alive, I had a school of 11 pygmy corys all die on me. and now my peppered corys are steadily dying one or so a week. The ONLY symptom any fish has ever displayed is flashing. Otherwise everyone current and past was and is active, eating, showing good color etc. After a full year I have concluded this is not being caused by a disease. Throughout the year I have treated exactly according to directions with kanaplex/furan 2 for possible columnaris. I have used paraguard, sulfaplex, stressguard, apI general cure, prazipro, salt baths, temperature raisings...the whole works and still the flashing and cory deaths persist. Every time I introduce new fish they begin flashing IMMEDIATELY when added to the tank....it seems a disease would take time to effect the fish to cause it to flash so I feel like it has to be something in my tap water which has roughly the same readings as the tank. Does anyone know of any possible culprits that would be in tap water that would irritate fish...and especially corys?? I have had the gudgeons and rasboras for a few years so whatever is going on is not killing them but they are still being irritated by something

 

What kind of substrate exactly do you have? The fact that your bottom-dwelling cories were more affected than the mid-level swimming rasboras makes me think something is leaching out of the soil.

 

What are you using to test the water? What type of filtration? What filter media are you using and do you clean/replace it? If so how often?

 

excess chlorine and chloramins in ur tap water can cause erratic swimming also.

 

I read your first sentence, and I thought it would be a dirted tank. And then it was.
9 times out of 10, a dirted tank with non digging fish works like a charm. With the 1 in 10 seems to involve flashing. It's what I saw with my first dirted tank.
Something was coming out of the soil I used that caused irritation, and eventually, the death of the fish. A pesticide? A fert? I never knew what.
It is a tried and true fishkeeping technique, but it is not perfect. I suspect the soil.

 

Your list of treatments reads as Chemical Soup. I agree the filtration and substrate may be holding onto a problem for your corys. Big water changes are in order to dilute the salts and chemicals.

 

I don't know much abut the ill effects of a dirt tank but it solnds ike tit time to eliminate it as a possibility. And yes a few WCs to get the random chemistry experiment completely out of the tank.

 

Thanks for the responses everyone! The soil is miracle grow organic mix, what I have read most people use and it is capped with petco black sand. Filtration is two 5-15 aquatech hob filters using the provided media and added lava rock for filter media (switching to ceramic rings eventually)...I removed the carbon packs that came with the filters and use polyfil for mechanical filtration. The various treatments were dosed over the course of a full year and always a few weeks in between treatments using carbon to extract medication in water. I do twice weekly water changes, one 25% on 40% w.c. I use seachem prime for dechlore...I have long suspected dirt has been leeching something irritating the fish and dreading undertaking the project of removing it as my plants are doing so good and finally filling in lush and thick and growing like crazy! But I feel like I have ran through the gauntlet of potential diseases and coming down to having to remove the dirt....I want healthy happy fish first and healthy plants second