Why Are My Aquarium Plants Melting?
Leaves going soft, see-through and falling apart? Here’s why aquarium plants melt, when it’s normal, and when it’s a sign of a problem.
“Melting” is when leaves go soft, translucent and slowly fall apart. It’s one of the most worrying things to see in a new planted tank, but it’s often completely normal. The trick is telling normal melt from a real problem, and the timing usually gives it away.
Cause 1: The plant is switching to underwater leaves
Most plants sold in the UK are grown emersed, out of water, in nurseries. Their leaves are built for air. Once submerged, the plant grows new underwater leaves and drops the old ones. This happens in the first two to six weeks after planting. As long as you see new growth coming from the centre or the stem tips, the plant is fine. Trim off the melting leaves so they don’t rot in the tank.
Cause 2: Crypt melt
Cryptocoryne are famous for it. Move them, change the water a lot, or change the light, and they can drop every leaf in days. Don’t pull them out. The roots are almost always alive and will send up new leaves within a few weeks. Add a root tab nearby and leave them alone.
Cause 3: Hungry plants
If plants melt in an established tank that hasn’t changed, it’s often a nutrient shortage. Potassium is a common one: leaves develop small holes and see-through patches, then break down. A general shortage across the board makes older leaves fade and dissolve while the plant moves its food to new growth.
| What you see | Likely cause | Fix |
|---|---|---|
| Old emersed leaves melt in weeks 1–6, new leaves look healthy | Normal transition | Trim old leaves, keep dosing |
| Crypts drop all leaves after a move | Crypt melt | Leave the roots, add a root tab |
| Holes, then melting, on older leaves | Low potassium | Increase macro or add potassium sulphate |
| Whole plant fading and melting slowly | General shortage | Check you’re dosing daily at the right level |
| Melting after a big change in water | Shock | Smaller, more regular water changes |
Not sure which it is? Our yellow leaves guide helps you read the signs.
Cause 4: Sudden changes
Big swings in temperature, a large water change with very different tap water, or switching to a much stronger light can all trigger melting. Plants like stability. Make changes gradually and keep your water changes consistent in size.
Cause 5: Not enough light
Plants that need medium or high light will slowly melt away in a dim tank. Red stem plants and carpets are the usual victims. Either give them more light or swap them for low-light species such as java fern, anubias, crypts and mosses.
If a plant was fine for months and starts melting, something in the tank has changed: food, light, temperature or water. Work through them one at a time.
What to do with melting leaves
Trim them off at the base. Rotting leaves release waste that feeds algae and can cloud the water. Keep dosing as normal, because the plant needs food to grow its replacements. Don’t move the plant again, as that restarts the stress.
Quick answers
Will a melting plant grow back?
Usually yes. As long as the roots or rhizome are firm and healthy, the plant will grow new leaves within a few weeks.
Should I stop plant food while plants are melting?
No. Plants need nutrients to grow new leaves. Keep dosing at your normal level.
Why are my new plants melting?
Most shop plants are grown out of water. They drop their air-grown leaves and grow new underwater ones. It’s normal in the first few weeks.
Can fertiliser cause plants to melt?
Not at the normal dose. Melting is far more often caused by too little food, sudden changes, or the switch to underwater growth.
Products mentioned in this guide
Everything to start dosing on day one: pre-measured macro and micro compounds, two 500ml bottles, two dosing syringes and a full dosing guide.
Potassium boostAdds potassium without adding nitrate. Ideal when fish already supply plenty of nitrogen.
Nitrogen + potassiumThe main source of nitrogen and potassium in your macro bottle. Usually the first compound to run low.
Copper-free aquarium plant food.
Dose on day one.
Pre-measured compounds, bottles, syringes and a full dosing guide. Shrimp safe, made in the UK, free UK delivery on every order.
Everything you need to get the most from your planted aquarium.
