Will a bristlenose pleco eat my cardinal tetra eggs or fry?

Bristlenose plecos are primarily herbivores that graze on algae and biofilm. They may opportunistically eat eggs or tiny fry, but they will not actively hunt adult tetras.

How many cardinal tetras can I keep with one bristlenose pleco?

Start with six cardinal tetras as a school. In a 20-gallon tank, this is a full bioload with a bristlenose present. Upgrade to 30 gallons if you want to keep more.

Do bristlenose plecos need driftwood to stay healthy?

Yes. Driftwood provides fiber that bristlenose plecos need for digestion. Without it, they may develop digestive problems. Supplement with zucchini or other vegetable matter weekly.

Can Bristlenose Pleco Live With Cardinal Tetra?

By Alex WalshLast reviewed Apr 18, 2026

It depends

Maybe, with caveats , bristlenose plecos and cardinal tetras share parameter ranges and occupy opposite tank levels, which reduces conflict, but plecos produce significant bioload for their size.

Why

Temperature overlap of 73-81°F covers both species comfortably, with bristlenose preferring the cooler end.
pH overlap of 6.5-7.0 suits both species well, leaning toward slightly acidic water.
Bristlenose plecos are bottom dwellers while cardinal tetras school in the middle water column, so they rarely interact directly.
Bristlenose plecos grow to 5 inches and produce a heavy bioload relative to their body size.
A 20-gallon tank is workable for a single bristlenose, but adding a school of cardinal tetras pushes bioload significantly.

Minimum shared tank

20 gallons

Shared temperature range

73-81°F

What could go wrong

Bristlenose plecos are messy eaters that cloud water quickly, and cardinal tetras need clean water to show their colors and stay healthy.

Gear for a shared tank

Sized for the 20 gallon minimum this pairing needs. Affiliate links — we earn a small commission if you buy through them.

AquaClear 30 Power Filter

Oversized filtration is what lets you stock two species together without water quality crashing. Rated for a tank slightly larger than the 20 gallon minimum.

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Eheim Jager 150W Thermostat Heater

Holds a steady temperature inside the 73-81°F window both species need.

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API Freshwater Master Test Kit

Keep ammonia, nitrite, and nitrate in check. Two-species tanks have more bioload and less margin for error than single-species setups.

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Better pairings to consider

Bristlenose plecos do well with corydoras, otocinclus, or other bottom dwellers. Cardinal tetras do well with rummy-nose tetras, ember tetras, or rasboras.