In reply to Brad …. Yes, you are 100% correct. I’ve had the same problems with mollies and guppies. They slowly die out in my community tanks. Then every once in a while you run across some one who can’t slow down the breeding of guppies and molies and gives them away. These folks have happened on strains’ which are hardy.

I have had a few fish die slowly, showing signs of deterioration/wasting, then lethargy, and then death. This has been seen in my Mollys and Guppies—as you have said in one of your chapters, they are not hardy fish anymore. But one does worry about the environment.

My Cardinal tetras ( 1 year) have been in the aquarium and look very healthy and no deaths have occurred. Would you say that if the Cardinals being Blackwater fish, are healthy and thriving that the chances are the slow Molly and Guppy deaths are due to their inherent weaknesses?

Thanks as always,
Brad

In reply to Tathagata …. It is probably just the heat. Only good solution is to add a cooler.

The only thing that’s changed was the climate at the onset of a very dry and hot summer !

I can’t get my tank water temperature below 28C using evaporation with fans and the TDS is roughly 900.
The water has become a little dull recently indicating bacteria in the water column.

Could this be due to the TDS or temperature ? Is there a correlation ?

In reply to Nick …. Start out with low stocking and get your Java Fern and Amazon sword growing well first. Then add more and more stock over a period of months as the plants take hold.

I fear this will be me : “A surprising number of times the problem is that the hobbyists are trying to keep moderate amounts of fish with plants. The aeration a moderate amount of fish need is decidedly detrimental to the growth of plants, killing them slowly over months. These slowly dying plants release dissolved organic compounds which feed bacterial growth in the water column (i.e. “dull” water). The bacterial growth kills fish slowly in a variety of ways.”

Building a 29 gallon with under gravel filter and 3 inches of gravel and 2 power heads and internal cartridge with foam only media, for filters, I was hoping to moderately stock it ( 2 apos, 2 loaches and 2 schools of 10 fish (10 tetras an 10 pencilfish).
It is meant to be a low tech moderately planted tank (only java fern and amazon swords) with low lighting (6 hours).

Now I am worried the plants will slowly die (with the consequences you explained).

Is there no plants that can survive high areration (low CO2), low tech tank with moderated fish stocking?

In reply to Jo … Overfeeding and under filtration are your probable causes. Cut back on the food and add a sponge filter for a while. Note I routinely do 90 to 95% water changes with no effect on the fish.

I have platies and danios in a cold water tank. The danios are all fine but the platies are very slowly swimming at the bottom or edge of the tank then dying one by one since the last (too big) water change.

Water tests are all ok.

If I’m right that I’ve got too little “good” bacteria and maybe a disease going round, what can I do about it? Presumably if I replace the platies before sorting it, they’ll just die too.

In reply to Chris …. I’m not big on frozen fish food. The food commonly gets “unfrozen” at some point and spoiled frozen fish food is VERY common. And that will kill fish.