Renny's ricefish
Oryzias hadiatyae
Renny's ricefish exhibits a slender body, reflective silver scales, and a distinctive rounded dorsal fin with black markings.
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About the Renny's ricefish
This is a little Sulawesi ricefish that only comes from one spot - Lake Masapi - and it lives right up in the roots and shoreline tangles. The neat giveaway is the concave dip on the snout, plus males can show dark brown blotches along the side, so its got more character than most "silver minnows" people expect.
Also known as
Quick Facts
Size
4.6 cm
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
20 gallons
Lifespan
3-5 years
Origin
Southeast Asia (Sulawesi, Indonesia)
Diet
Omnivore/micro-predator - small insects and larvae, tiny crustaceans, quality micro-pellets and frozen foods
Water Parameters
24-28°C
6-7.5
1-10 dGH
Need a heater for this species?
This species needs 24-28°C in a 20 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Give them a long tank with lots of horizontal swimming space (10-20g+), plus a lid - they jump when startled.
- They do best in cooler freshwater: aim for about 72-78F, and keep pH roughly neutral to slightly alkaline (around 7.0-8.0) with steady hardness - they get touchy if your water swings.
- Pack the tank with fine-leaf plants or spawning mops and some floaters; they color up and act way less skittish when they have cover near the surface.
- Feed small foods 1-2 times a day: baby brine shrimp, daphnia, cyclops, and good micro-pellets; they look skinny fast if you rely on big flakes only.
- Keep them in a group (8-12+) or they act nervous and hide; more fish spreads out the chasing and you see better behavior.
- Tankmates: tiny, calm stuff only (small rasboras, other gentle ricefish, peaceful shrimp). Skip fin-nippers and fast hogs like many danios or barbs, and avoid big hungry fish that will treat them like snacks.
- Breeding is easy once they settle: females carry a little clump of eggs, and they will scatter them in mops/plants; pull the adults or pull the eggs if you want fry because they will snack on them.
- Watch for velvet/ich after temp swings or new fish - they are not forgiving; quarantine newcomers and keep the tank stable rather than chasing numbers.
Compatibility
Good Tankmates
- Small, chill nano schoolers like ember tetras or green neon tetras - they match the same calm vibe and wont hassle the ricefish at the surface
- Other peaceful micro fish like chili rasboras or celestial pearl danios - similar size and temperament, and they look great sharing the top and midwater
- Pygmy Corydoras (pygmaeus/habrosus/hastatus) - gentle little bottom crew that wont compete with them and keeps things active without stress
- Otocinclus - super peaceful algae grazers that just do their own thing and dont spook a timid ricefish group
- Small, non-nippy livebearers like Endlers (not the big pushy guppies) - they can share space fine as long as the tank isnt crowded
- Cherry shrimp or Amano shrimp - ricefish are usually pretty polite, but expect the tiniest shrimplets to be snacks if they can fit in a mouth
Avoid
- Fin nippers and speed demons like tiger barbs or serpae tetras - theyll harass these peaceful little guys and keep them pinned in the corners
- Big-mouthed predators like bettas (some are fine, plenty are not), dwarf cichlids, or anything that can swallow a ricefish - risk goes way up fast
- Goldfish - wrong temps, messy water, and theyll outcompete them at feeding time
Where they come from
Renny's ricefish (Oryzias hadiatyae) is one of those ricefish that made the hobby world do a double-take once it started showing up. They're from Sri Lanka, and in the wild they hang around warm, weedy, lowland freshwater - think slow water, a lot of plant cover, and plenty of tiny critters to pick at.
They look "easy" because they're small and peaceful, but the trick is they really don't love being shoved into generic community conditions. They're pickier than most folks expect, and that's why I call them advanced.
Setting up their tank
If you want them to settle in, give them a calm, planted tank and keep the water stable. I had the best luck treating them like a small, shy schooling fish that hates sudden change.
- Tank size: 10-20 gallons is a comfortable starting point for a group. Bigger is always easier to keep steady.
- Group size: 8-12+ if you can. They act way more natural in numbers.
- Filtration: gentle. Sponge filters or a baffled HOB work well. They don't enjoy getting pinned in a current.
- Plants: lots. Floaters up top plus fine-leaved plants or moss is perfect.
- Cover: give them shade and edges - wood, plant thickets, leaf litter if you like that look.
- Lighting: medium to low. Bright light with no cover tends to keep them jumpy.
They jump. Not "sometimes" - they jump. Use a lid, block gaps around wires, and keep the water line a little lower than usual.
Water-wise, stable beats chasing numbers. Aim for warm-ish tropical temps (mid 70s F is a nice ballpark) and avoid big swings. I usually do smaller, more frequent water changes rather than big ones, especially early on.
If you're bringing in a new group, dim the lights the first day, add extra floaters, and feed lightly. They calm down faster and you get fewer losses from shipping stress.
What to feed them
Mine never did great on "just flakes". They'll eat them, sure, but they really color up and fill out when you feed like you're stocking a nano predator - small foods, variety, and frequent tiny meals.
- Daily basics: quality micro pellets, crushed flake, and small granules they can actually fit in their mouths.
- Best conditioners: live or frozen baby brine shrimp, cyclops, daphnia, and finely chopped bloodworms (not huge pieces).
- If they're being fussy: live foods usually flip the switch, especially after shipping.
- Feeding style: 1-2 small feedings a day beats one big dump. They pick at food in the water column.
If food hits the bottom and sits, you're overfeeding or the flow is too low. These fish are cleaner midwater feeders than "bottom scavengers".
How they behave and who they get along with
They're peaceful and pretty polite, but they're not bold. In a busy community tank they can get outcompeted and slowly fade out. In a calm tank, you see the real behavior: schooling, little squabbles between males, and lots of hanging under floaters.
- Good tankmates: other gentle nano fish that don't rush food (small rasboras, small tetras with calm temperaments), small peaceful shrimp, and snails.
- Avoid: fin nippers, fast feeders, larger "curious" fish, and anything that treats them like snacks.
- Best setup: species-only or a quiet nano community where they aren't constantly pushed around.
Even if aggression isn't obvious, fast tankmates can starve them out. Watch feeding time - if your ricefish hang back, change the plan (more cover, different tankmates, target feeding, or a species tank).
Breeding tips
Ricefish are fun because they breed in a very "fishkeeper-friendly" way. Once they're settled and eating well, you'll often see eggs without trying too hard. Females will carry a small cluster for a bit, then drop or attach them to plants or spawning mops.
- Spawning setup: a clump of java moss, a floating spawning mop, or fine plants near the surface.
- Collecting eggs: check plants/mops daily. You can move eggs to a small container with gentle aeration.
- Fry food: infusoria or powdered fry food the first days, then baby brine shrimp soon after.
- Keep it clean: fry tanks get nasty fast. Small water changes and light feeding keep losses down.
If you want to actually raise numbers, pull eggs or move adults. Adults aren't piranhas, but they'll still pick off tiny fry when they find them.
Common problems to watch for
Most issues I've seen with this species come down to stress and stability. They can look fine for a week, then start dropping if something is off.
- Shipping/transition stress: they can be touchy after arrival. Low light, lots of cover, and gentle flow help a lot.
- Jumping: the classic ricefish problem. A tight lid saves lives.
- Slow starvation: happens in community tanks or with food that's too big. Watch bellies and feeding behavior.
- Temperature swings: small tanks swing fast. Heaters fail, rooms cool down at night - they notice.
- Gunk buildup: overfeeding micro foods can foul a nano tank quickly. Keep an eye on ammonia and do smaller water changes more often.
If you see clamped fins, hiding at the surface, or rapid breathing, don't just medicate. Check ammonia/nitrite first, then look at flow, temperature swings, and whether they got bullied off food.
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