Rosy Loach
Petruichthys sp. "rosy"
Also sold as Dwarf rosy loach
Rosy Loach (Petruichthys sp. "rosy") is a peaceful freshwater fish that reaches about 3 cm (1.2 in) and swims along the bottom in a shoal. It wants 68–79°F (20–26°C) and pH 6.5–8, is kept in groups of 8 or more, and needs a tank of at least 54 L (14 gal).
At a glance
| Type | Fish |
|---|---|
| Adult size | 3 cm (1.2 in) |
| Minimum tank | 54 L (14 gal) |
| Group size | 8 or more |
| Temperature | 68–79°F (20–26°C) |
| pH | 6.5–8 |
| Temperament | Peaceful |
| Eats shrimp | Shrimplets only |
Before it goes in
- Rosy Loach needs at least 54 L (14 gal). The smallest size in this library that clears that is the 15 Gallon.
- Keep 8 or more. Below that it hides, colours down and is far more likely to be picked on.
- Adult shrimp are safe; shrimplets will be eaten, so a shrimp colony will not grow in the same tank.
- It holds at 68–79°F (20–26°C). That shares a window with Betta and Cherry Shrimp, but not with Discus.
- Sources say not to put it in a newly set-up tank — give the tank a few months first.
- A group of 8 takes up roughly 44% of what a 15 Gallon will comfortably hold, so plan the rest of the stock around it.
What tank size does it need?
At least 54 L (14 gal). The smallest size here that clears it is the 15 Gallon.
How many should I keep?
8 or more. Fewer than that and it spends its time hiding instead of out in the open.
Will it eat shrimp?
Adults are safe, shrimplets are not. You can keep shrimp with it; you just will not get a growing colony.
What water does it want?
68–79°F (20–26°C), pH 6.5–8.
Can it go in a new tank?
No. Sources say not to add it to a newly set-up tank — it wants a tank that has been running for months.
Good tank mates
- Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Cherry Shrimp, Goldfish, Bristlenose Pleco, Celestial Pearl Danio and Molly.
- Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.
Often compared with
| Rosy Loach | Borneo Sucker Loach | Dwarf Chain Loach | |
|---|---|---|---|
| Adult size | 3 cm | 4 cm | 6 cm |
| Min tank | 54 L | 54 L | 75 L |
| Group | 8+ | 1+ | 6+ |
| Temperature | 68–79°F (20–26°C) | 68–75°F (20–24°C) | 75–82°F (24–28°C) |
| Eats shrimp | Shrimplets only | Shrimplets only | Yes |
More livestock
Sources (3) · checked Sep 2026
- What it eatsaquariumstoredepot.com
- Mature tankseriouslyfish.com
- What it eatstankora.co.uk