Gold Laser Cory (Osteogaster sp.) — CW010

Gold Laser Cory at a glance

The Gold Laser Cory is a small freshwater catfish traded under the aquarium code CW010 and now placed in the genus Osteogaster. Each purchase is one live fish, in a choice of three dispatch sizes: 2–2.5 cm, 2.5–3 cm or 3–4 cm. It is a shoaling bottom-dweller, so the deciding question is space: OATA recommends at least 80 litres for a shoal of Corydoras-type catfish and a group of at least five, in an aquarium whose filter is already mature. Its appeal is a shoal moving together across the floor of a planted community aquarium, and that is the picture to plan for.

The size you select is the size supplied, not the adult size. Whichever size you choose, set the aquarium up for fully grown fish from the start: each needs the same water, the same space and the same company as the adult shoal it will join. Choose the size that suits your plans for the group rather than expecting a larger fish to need less care.

Names, codes and the genus

This fish has been sold as Corydoras sp. CW010, and the trade name Gold Laser Cory comes from the aquarium trade. CW010 is a code for a recognisable aquarium form, not a species name. A primary classification paper in the Zoological Journal of the Linnean Society, available through its record on Zenodo, shows the same coded form, written there as CW10, in its Figure 20 as Osteogaster sp. That is why the scientific name on this page stops at the genus.

The exact species has not been identified, so the care advice here follows the genus Osteogaster and its care group. In practice, that care group is the one OATA's freshwater catfish sheet covers, and the sheet names Corydoras directly when it gives advice on shoal size, tank size and diet. Shops and supplier lists often still use the Corydoras label, so you will see both names used for this fish.

What you receive

One purchase supplies one live Gold Laser Cory of the size you choose, so the quantity in your basket is the number of fish that will arrive. Each size is a separate option, and the product page shows which sizes can be ordered at the time you buy. If you are comparing this fish with other catfish before deciding, our Corydoras collection brings the related fish together in one place.

Sex is guaranteed only when the selected option explicitly states male or female. This Gold Laser Cory listing has no sex-guaranteed option. OATA notes that sexing catfish can be difficult, and young fish of this size are not sold by sex, so a group bought together has no set balance of males and females.

Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals. The gallery shows the gold stripe along the upper body that gives the fish its trade name, above a dark band and paler underside. Individual fish will differ from the pictures in brightness and markings.

Before you order

• Check that your aquarium has room for at least five of these catfish, not just the one or two you might buy first.
• Confirm that ammonia and nitrite read zero in a filter that has been running with fish or a planned load.
• Make sure every fish already in the tank is peaceful and suits the same water range.
• Decide whether to buy the whole group at once or build it in stages, and check that the filter can cope with the full number.

Aquarium size, filtration and furnishing

A shoal of small catfish needs floor space, clean water and somewhere to rest out of view. Get those three right before the first fish arrives and the rest of the care becomes routine.

How big an aquarium?

OATA's care sheet for freshwater catfish recommends buying an aquarium as large as is reasonably possible and suggests at least 80 litres for a shoal of the smaller species, such as Corydoras or the smaller plecos. Bigger catfish need much larger tanks, which is one reason OATA asks buyers to check a catfish's needs before purchase. The larger the aquarium, the more stable its temperature and water quality will be.

Think about the bottom of the tank as well as its volume. These are fish that live and feed near the floor, so the area left open once wood, rock and plants are in place is the space the shoal will actually use. A long aquarium with an open front area gives a group room to move and feed together.

Filtration and a mature aquarium

A filter is always essential. The RSPCA's guidance on the aquarium environment explains that a working biological filter allows beneficial bacteria to grow and break down waste naturally: ammonia is converted to nitrite, which is also toxic, and then to the safer nitrate. A filter only reaches that state once the bacteria have established, which is why the aquarium should show zero ammonia and nitrite on test before any catfish are added. Our guide to setting up a first tropical tank takes you through filling, maturing and testing a new aquarium step by step.

Plants, cover and shelter

• For smaller or shyer catfish, OATA suggests that the tank should ideally have live plants to provide cover.
• Some catfish may eat or dig up live plants, so OATA recommends adding plastic plants and suitable ornaments as well.
• Many catfish appreciate shelter in the form of wood, pots or caves, which gives a shoal somewhere to rest between bouts of activity.
• Keep an open area at the front where sinking food lands, so you can watch every fish feed and spot any that hang back.
• Choose décor with smooth edges and openings large enough that a small catfish cannot become wedged.

An order of work for a new set-up

1. Choose an aquarium of at least 80 litres, larger if other fish will share it.
2. Install the filter and heater, then add plants, wood and shelter while leaving an open feeding area.
3. Run the aquarium until tests show ammonia and nitrite holding at zero.
4. Add fish gradually, testing after each addition, until the Gold Laser Cory shoal reaches five or more.

OATA also advises care when handling catfish, because most have spines. Move a Gold Laser Cory gently and avoid lifting it in a fine net where the spines can catch; guiding it into a container is kinder than chasing it round the tank.

Water quality and temperature

OATA describes catfish as usually undemanding of water chemistry, and its care sheet for freshwater catfish gives the planning ranges below. They are broad guidance for catfish as a group, written to cover many species, so treat them as the outer limits of a stable aquarium rather than a target to move between.

Why zero ammonia matters so much

OATA's maintenance advice warns that some catfish can be stressed by even the smallest amounts of ammonia. For a fish that spends its life close to the substrate, where uneaten food and waste collect, that makes regular testing and careful feeding part of basic care rather than an extra. If a test ever shows ammonia or nitrite above zero, stop and find the cause before adding more fish or food.

Nitrate and your tap water

OATA's nitrate figure is relative rather than absolute: nitrate should not exceed 20 mg per litre above your normal tap water level. That means testing the tap water for nitrate as well as the aquarium. If the tap reads 10 mg per litre, for example, the aquarium should stay at or below 30 mg per litre. Weekly partial water changes, careful feeding and a sensible number of fish are what keep it there.

Holding a stable temperature

A 22–27°C range is warmer than many UK rooms, so a correctly sized aquarium heater with a thermostat is normally part of the set-up. Pick one steady temperature inside the range that suits every fish in the tank, check it with a thermometer you can read at a glance, and watch for summer heat as well as winter cold.

Testing your own water

Measure your aquarium rather than assuming your tap water fits. Our guide to aquarium water parameters explains what each test tells you, and the water parameter matcher lets you set your readings against the planning ranges above, which is especially useful when you are choosing tank mates for a shared aquarium.

Feeding a Gold Laser Cory

OATA describes Corydoras as omnivorous, and it is clear about one common misunderstanding: although catfish have a reputation as scavengers, they should be fed appropriate sinking foods so their nutritional needs are met. A Gold Laser Cory is not a clean-up crew that lives on scraps; it needs its own food, delivered to the bottom where it feeds.

How much and how often

OATA's catfish sheet advises feeding only what the fish can eat within a few minutes, once a day, and taking care not to overfeed. Uneaten food breaks down and releases toxic waste into the water, and on the floor of the aquarium it sits exactly where a shoal of bottom-dwellers spends its time. If in doubt, OATA suggests asking your retailer about feeding levels for the particular fish.

Making sure food reaches the shoal

• Use sinking foods sized for the smallest fish in the group.
• Drop food in more than one place so that every catfish can reach some without being crowded out.
• Watch a complete feed from time to time and check that each fish is eating.
• If quicker fish take food before it settles, feed them first and then add the sinking food.
• Remove anything still lying on the bottom after the feed, rather than leaving it to decay.

Body condition is a good guide over weeks. A fish that is steadily losing weight, or showing less interest in food, matches two of the warning signs OATA lists, and it is worth testing the water and reviewing how food is reaching the bottom before anything else.

Routine care and health checks

The weekly routine

• Carry out a partial water change of 25% at least once every week, which OATA strongly recommends; a siphon makes it easy to lift solid waste from the gravel.
• Test the water at least once a week so that ammonia and nitrite do not build up unnoticed.
• Treat replacement water with a tap water conditioner to remove chlorine and chloramine before it goes in.
• Check the filter for blockages. When it needs cleaning, rinse it lightly in tank water removed during the water change; do not run it under the tap, because chlorine or chloramine can kill the beneficial bacteria.

OATA sums this up simply: good husbandry is essential. A steady, repeatable routine protects a shoal far better than an occasional major clean.

Signs worth noticing

All fish vary slightly in behaviour and appearance, but OATA lists changes that help identify a problem before it becomes a real health issue:

• Swimming: hanging at the surface, sitting on the bottom more than usual, or erratic swimming.
• Colour: turning darker or paler than normal.
• Temperament: changes in aggression, or hiding more than normal.
• Breathing: gill covers moving faster or slower than normal.
• Appearance: white spots or fluffy growths, or loss of fins.
• Condition: an increase or decrease in body weight and condition.
• Feeding: reduced intake or lack of interest in food.

If you are concerned about any of your fish, OATA's first step is to test your water quality and then seek further guidance from your retailer. Record what you see with dates and photographs; a clear record makes it far easier to work out whether a change is spreading through the group or affects a single fish.

A monthly review

• Count the shoal and look at each fish against OATA's description of a healthy fish.
• Compare recent test results and look for slow trends, especially in nitrate.
• Check that filter flow has not dropped and that the heater is still holding temperature.
• Ask whether the aquarium is still stocked within its capacity as the fish grow.

How long they live

OATA says that catfish, whatever their size, can live for several years in a well-matured set-up with good water quality. That is guidance for the whole group rather than a promised lifespan for this fish, but it is a fair picture of the commitment involved in keeping a shoal.

Building and growing a shoal

Because OATA advises keeping Corydoras in groups of at least five, the real purchase is a shoal rather than a single fish. Plan the finished group first, then work out how to reach it without overloading the aquarium.

Adding fish gradually

OATA recommends increasing the number of fish only slowly, because the beneficial bacteria in a matured filter need to increase every time more fish are added and feeding goes up. Overstocking, or stocking too quickly, can result in “new tank syndrome”: there are not enough nitrifying bacteria to cope with the extra waste, ammonia and nitrite rise to unhealthy levels, and fish can become ill or die. Test the water after each addition and wait for zero readings before the next.

What a healthy fish looks like

OATA's description of a healthy fish is a useful checklist when new catfish arrive: clear, bright eyes, undamaged fins, no ulcerations or bumps, and appropriate swimming behaviour. Compare each newcomer with that list over the first days, and with the fish already in your group.

Why group size matters

OATA's warning is direct: Corydoras kept singly, or in groups that are too small, will often become stressed. If you can only buy part of the shoal at first, keep the gap short and make sure the aquarium can take the full group before starting.

Recognising stress in a small group

Stress is not always dramatic. The early warning signs OATA lists, such as hiding more than normal, turning paler or darker, losing interest in food or losing condition, are also the ones to watch when a group is too small or the tank does not suit it. If several fish show them at once, test the water first, then look at group size, cover and feeding.

Delivery, arrival and settling in

Our team hand-packs every order. Each fish is bagged in pure oxygen and packed in an insulated poly box, with a heat pack added when the weather calls for it. The parcel travels with a licensed live-animal courier on a tracked service, and we email the tracking number and your confirmed delivery date so that you know when to be at home. The full conditions sit on our delivery and Live Arrival Guarantee page.

Getting ready before delivery day

• Test the aquarium in the days before delivery and confirm that ammonia and nitrite read zero.
• Check that the heater is holding a steady temperature within the planning range.
• Put shelter, plants and the open feeding area in place now, not after the fish arrive.
• Arrange for someone to be at home to receive the parcel, with a phone ready to film the unboxing.
• Keep the tracking email to hand so you can follow the parcel once tracking is active.

When the parcel arrives

1. Someone needs to be at the delivery address to take the parcel in, as live fish cannot be left unattended.
2. Film one continuous unboxing video that starts with the sealed outer box, shows it being opened, and ends with the fish still inside the sealed bag.
3. Check the fish in the bag straight away; the guarantee requires the parcel to be opened and inspected on the day it arrives.
4. Acclimatise slowly: float the sealed bag in the aquarium for 20–30 minutes before releasing the fish.
5. Never pour the bag water into your tank; move the fish across without it.
6. If anything has gone wrong, contact us the same day, with WhatsApp the quickest route, sending your order number and the unboxing video so we can arrange a replacement or refund.

The first days

New arrivals may look for cover at first, so make sure the shelter described above is in place before they arrive. Hold back on food for newcomers until they are moving about, then feed lightly and remove leftovers. Keep testing through the first weeks, especially if the new fish have taken the group to its full size, and compare each fish with OATA's list of healthy signs.

Choosing tank mates

OATA's catfish sheet puts Corydoras among the catfish that make excellent additions to community aquariums, and that is the natural home for a Gold Laser Cory: a shoal working the floor of a peaceful mixed tank. The same sheet is a reminder of why checking still matters. Catfish as a whole range from small and peaceful to large and predatory, some species can be extremely predatory and should be mixed with caution, and OATA advises consulting your retailer before adding catfish to a community aquarium.

What to check before mixing

• A shared water range: every fish in the tank needs to be comfortable within the same temperature, pH and hardness.
• Temperament: predatory species, and any fish large enough to treat a small catfish as food, need real caution.
• Feeding: quick midwater feeders can leave little for the bottom unless you feed with care.
• Floor space: other bottom-dwellers share the same open area and the same sinking food.
• Shoal first: complete the group of five or more before filling remaining space with other fish.

Other catfish

OATA names Otocinclus and smaller plecos alongside Corydoras as catfish that make excellent additions to community aquariums. That does not make every catfish a suitable partner. Plecos and other bottom-dwellers compete for the same floor and food, and larger or predatory catfish belong in a different kind of aquarium altogether. Treat any mixed catfish community as a question of space and feeding as much as temperament.

A peaceful community

The simplest successful plan is a mature, planted community aquarium with the Gold Laser Cory shoal on the bottom, peaceful fish that share its water above, and a feeding routine that gets sinking food to the floor. Watch the tank closely whenever a new species is added, and have a plan for moving fish if behaviour changes.

When a pairing is not working

Watch the catfish closely for the first weeks after any new tank mate goes in. Warning signs include the shoal hiding far more than before, fish losing weight because food never reaches them, or damage such as loss of fins, which OATA lists among the signs of a health problem. If you see them, act early: change how you feed, add cover, or move the fish causing the problem to another aquarium.

Gold Laser Cory questions and answers

How big does a Gold Laser Cory get?

Its adult length is not something we can confirm, because the fish is known only by an aquarium code and its exact species has not been identified. OATA counts Corydoras among the smaller catfish, so plan the aquarium for a shoal of small adult bottom-dwelling catfish rather than for the size of the fish that arrive.

What size aquarium does a Gold Laser Cory group need?

OATA recommends an aquarium of at least 80 litres for a shoal of the smaller catfish species, such as Corydoras. A larger tank keeps temperature and water quality more stable, and a filter is essential whatever the size. Plan the space for the adult shoal and every other fish you intend to keep, not for the first few arrivals.

How many Gold Laser Corys should I keep together?

Keep a group of at least five. OATA describes Corydoras as shoaling fish and warns that those kept singly or in groups that are too small will often become stressed. Build the group in stages so the filter can keep up.

Is it a good choice for a beginner?

It can suit a newer keeper whose community aquarium is already mature, with measured zero ammonia and nitrite, and who has room for a proper shoal. The harder parts are planning enough space for five or more and making sure sinking food reaches the bottom, not the water chemistry itself.

What does a Gold Laser Cory eat?

OATA describes Corydoras as omnivorous. Despite the scavenger reputation, feed appropriate sinking foods so the fish meets its nutritional needs, giving only what the group can eat within a few minutes, once a day, and removing anything left over. If faster fish share the tank, feed them first so the sinking food reaches the bottom.

What temperature and pH does it need?

OATA's broad guidance for freshwater catfish is 22–27°C, pH 6.0–8.0 and a general hardness of 4–18 °dH, with ammonia and nitrite at zero. These are group-level planning ranges, so choose stable conditions inside them that also suit every other fish in the tank. In most UK homes that temperature range needs a thermostatic heater.

Is it aggressive, or likely to nip fins?

No. OATA names Corydoras among the catfish that make excellent additions to community aquariums. The problems to plan for run the other way: quicker fish can take food before it sinks, and predatory species need caution.

Which fish can live with Osteogaster sp. CW010?

Peaceful community fish that share its water range are the usual choice, and OATA names Otocinclus and smaller plecos alongside Corydoras as good community catfish. Catfish as a group range from small and peaceful to large and predatory, so check any predatory species with care before mixing.

How does a Gold Laser Cory arrive alive in the UK?

It is hand-bagged in pure oxygen and packed in an insulated poly box, with a heat pack when the weather calls for it, then carried by a licensed live-animal courier on a tracked service. Be in to receive it, record one continuous unboxing video from the sealed parcel to the fish still in the bag, and float the sealed bag for 20–30 minutes before releasing. Any Live Arrival Guarantee issue needs that video and your order number on the day of arrival.

Names used for this fish

You may meet this fish under several labels in shops and supplier lists. They all point to the same aquarium form, but each tells you something different.

Trade names can vary from shop to shop, so when you compare fish from different sellers, match the code as well as the common name. It is the simplest way to be sure you are looking at the same form, and to keep a shoal made up of one kind of fish.

Sources and further reading

These public sources support the identity and care details on this page. OATA's figures cover freshwater catfish as a group and are presented that way above.

• Zenodo record for the classification paper (Zoological Journal of the Linnean Society, doi 10.1093/zoolinnean/zlae053), whose Figure 20 shows the coded form CW10 as Osteogaster sp.
• OATA: How to look after freshwater catfish, for water ranges, aquarium size, group size, feeding, maintenance, health signs, handling and compatibility.
• RSPCA: fish environment and filtration, for why a working biological filter matters.
• Our delivery and Live Arrival Guarantee page, linked in the arrival section above, for packing, courier and arrival steps.