Knodus victoriae

Where they come from

Knodus victoriae is a small South American characin, tucked away in quiet forest creeks and tributaries connected to the Amazon basin. Think tea-stained water, leaf litter, submerged roots, and patches of dappled shade. Seasonal rains swell those streams, so they are used to soft, clean water and gentle to moderate flow.

Setting up their tank

Give them length over height. A 24-30 inch tank (90-120 cm) works well for a group, with open swimming room down the middle and cover along the edges. They are quick and nervous at first, so a tight lid is a must.

• Group size: 8-12+ to keep them confident and colorful
• Temp: 74-80 F (23-27 C)
• pH: 5.5-7.2
• Hardness: 1-8 dGH, low KH
• Filtration: steady, well-oxygenated flow without blasting them around
• Water changes: 30-50% weekly, keep nitrates low

Use fine sand or small gravel, a few pieces of driftwood, and a scatter of catappa or oak leaves. Plants help a lot. I like a wall of stems or moss along the back and sides, with floating plants to knock down the light. They settle fast in tannin-stained, shaded tanks.

What to feed them

They have small mouths and do best with small, frequent meals. In my tanks they light up on a mix of quality dry foods and tiny live or frozen fare.

• Staple: fine flakes or micro-pellets (0.5-1 mm)
• Regular treats: frozen or live baby brine shrimp, daphnia, cyclops
• Occasional: mosquito larvae, grindal worms (rinse well and feed sparingly)

How they behave and who they get along with

Active midwater schooling fish. In a decent-sized group they cruise in loose formation, then bunch up if startled. Keep them in a shoal or they get jumpy and may pester slower fish.

• Good tankmates: small tetras and pencilfish, hatchetfish (with a lid), Corydoras, Otocinclus, peaceful dwarf cichlids like Apistogramma
• Use caution: long-finned bettas or guppies that might invite nips if the group is too small or underfed
• Avoid: large cichlids and anything that could swallow them
• Shrimp: adults are usually fine, tiny shrimplets may be snacks

Breeding tips

They are classic egg scatterers. You can get lucky in a planted display, but the adults will hunt eggs, so a separate setup pays off.

• Breeder tank: 10-15 gal, sponge filter, dim light
• Spawning medium: fine-leaved plants, moss, yarn mops, or a mesh/marble layer to drop eggs through
• Water: soft and slightly acidic (pH 5.8-6.5), 76-79 F (24-26 C)
• Method: condition a small group (2-3 males per female) on rich live/frozen foods, introduce in the evening, and give them the morning to spawn
• After eggs appear: pull the adults
• Incubation: roughly 24-36 hours; free-swimming in 3-4 days
• First foods: infusoria or dense green water for 2-3 days, then switch to freshly hatched brine shrimp and microworms

Common problems to watch for

• Jumping: they spook easily. Keep a tight lid and cover gaps.
• Stress-Ich cycle: new imports can break with Ich after a move. Quarantine and raise aeration during treatment.
• Washed-out color and hiding: light too bright or group too small. Add floaters, boost the shoal, or provide more cover.
• Gasping near the surface: low oxygen or high waste. Increase surface agitation and step up water changes.
• Bloating or stringy poop: overfeeding or internal parasites. Cut back food and consider a deworming plan in quarantine.
• pH swings: lots of tannins with low KH can drop pH fast. Test regularly and avoid big changes all at once.