My 20 gallon tank is 6 months old. I haven't had too many problems with it, just a few diatoms 2 months into cycling it. I added 4 Serpae tetras, a Golden algae eater, 2 shrimp and an Assassin snail over a period of 5 months (Assassin to control the smaller snails).

I gradually added various plants, but they have all, except for a few, slowly died, turning brown then black. The plants surviving do grow and have roots, but they look weak and scraggly. I have an Anubis which is hanging on and Java moss (which brought the snails, thanks to the store). I had a Japanese lily which I found beautiful when it was healthy but had to remove it, as it developed spindly growth and plenty of water roots, even though it was planted in the substrate.

The fish are doing well but the plants always look yellowing, transparent and have a weird crunchy feeling to them. I have a fine, natural gravel substrate of 2 inches and add liquid plant food twice a month. I do regular water changes and trim the growth, removing dead leaves. The little white snails don't seem to eat the plants but rather the algae. I was giving my tank 10-12 hours of light a day but reduced it to 8-10 hrs given that I started to have fine hair-like algae growth on the plants, appearing to strangle them.

I've had my parameters regularly tested at the fish store and all is in the norm. The water has a pH of 7.5. I originally had bogwood in it to reduce the pH but it turned the water a dark brown in spite of regularly changing the carbon filter, so I removed the wood. I have since added 2 clown loaches to control the snails, but my biggest concern are the plants! Any ideas would be greatly welcome as to the mystery of:

What could be wrong with my plants? They all tend to look mummified and sickly.

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    please update your question with this information.GH-KH-NITRATE of your water.what type of lights do you use(if possible post the light spectrum or color temparature)a picture is helpfull to diagnose the problem and where your water comes from is helpfull too(well water or surface water and location of where you live). Jul 18, 2019 at 6:09
  • That seem like a lot of work, I just have some organic soil = some plants/moss + led light in my tank with no filter and some fish, shrimps and snails. nothing ever dies, and I only top off the water due to evaporation
    – Huangism
    Jul 22, 2019 at 18:49
  • To alleviate the problem with the brown water when using the wood, boil the wood and replace the water and boil again, until the quantity of brown gets to acceptable levels. After this, the wood will still release some "brown", but the water will only have a nice golden hue.
    – virolino
    Aug 23, 2019 at 11:26
  • I think water plants do what they want , mostly give them light. I have sold to pet shops , valisnaria , cryptocorne , java fern,java moss , calurpa ( marine), etc; just took a bunch of hornwort, anachris and water sprite. But I have problems growing cryptocrne and valisnaria now and I failed to grow probably 2 dozen Amazon sword plants over the years. Just try different plants until something works. Sep 14, 2019 at 1:31
  • You did not post a picture, so I need to guess. Be careful that whatever is behind the tank tremendously affects the percieved color of the water. Try placing a (huge) white sheet of something, and then look again. I tell you this from experience. My mother wanted to throw my tank away on the grounds of the water being to dirty. I proved her wrong with the previously mentioned test. The wall tiles behind the tank were colored milk-coffee.
    – virolino
    Sep 16, 2019 at 6:42

1 Answer 1


If the fish and snails are healthy then the water is probably OK. The problem is with the lighting or the substrate. Are you using full spectrum light? As much like sunlight as possible? If so it may be a little too strong. The substrate could be too shallow, or the filter too efficient. You say organic soil. I would never use soil in a substrate in an aquarium with fish already in it. The faecal matter from the fish and snails should be enough to feed the plants. Of the hair like algal growth. It sounds horribly like sewage fungus, which suggests that you are killing the plants by overfeeding them.

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