Topaz Cichlid (Amatitlania myrnae)

Understand the Topaz Cichlid before choosing it

Topaz Cichlid is the trade name used here for Amatitlania myrnae, a freshwater member of the cichlid family. FishBase places the species in Cichlidae and records it as a benthopelagic tropical fish from the Atlantic slope of Central America. Its stated range runs through Costa Rica and Panama, from the Estrella River to the Cuarumo River.

The broader Amatitlania genus account describes these cichlids as native to Central American freshwater habitats. The recurring trade identity Cryptoheros myrnae may also appear in older aquarium catalogues, but the scientific name used throughout this page is Amatitlania myrnae.

Who should choose this fish?

Choose it when you are prepared to mature and test the aquarium before introduction, maintain a working biological filter, control feeding and assess companions individually. American cichlids vary considerably in temperament, so this is a fish for a keeper willing to observe behaviour rather than rely on a universal community label.

Its recorded adult length is compact compared with many American cichlids, but a short body does not remove the need for water volume, filtration or careful stocking. If you are comparing other fish before making that decision, browse our current cichlid collection and compare adult dimensions, water requirements and temperament one animal at a time.

Choose the dispatch size without mistaking it for adult size

One purchase quantity supplies one animal. Use the live size selector to choose the dispatch grade shown below and check which size can be selected for your order.

The size you select is the size supplied, not the adult size. Do not infer age, life stage, sex or eventual behaviour from a dispatch measurement. Plan the aquarium around the recorded adult maximum, then use the selected grade only to prepare for the animal arriving at that measurement.

Understand the offer limits

Sex is guaranteed only when the selected option explicitly states male or female. This Topaz Cichlid listing has no sex-guaranteed option.

The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal.

Review the delivery and Live Arrival Guarantee policy before arranging receipt. It gives the current dispatch days, delivery information and claim process in one place. Check the live size selector for the dispatch measurement attached to your order.

Plan around the decisive adult, water and space figures

FishBase records a maximum of 8 cm standard length for male or unsexed Amatitlania myrnae. Treat 8 cm SL as the adult-size planning reference rather than a promised final measurement for every individual. It is the number to use when comparing the fish with aquarium dimensions and the adult sizes of proposed companions.

OATA’s American-cichlid guidance gives 22–27°C, pH 6.5–8.0, general hardness of 4–12°dH and carbonate hardness of 3–10°dKH as group guidance rather than a species-specific optimum. FishBase separately records 23–26°C as the environmental range associated with the species. For routine aquarium decisions, work within the OATA envelope, keep changes gradual and test the actual water rather than estimating it.

The 120-litre figure is OATA’s planning reference for a pair of smaller American cichlids, not a guaranteed minimum for every layout or mix. Aquarium dimensions, filtration, existing livestock and individual behaviour can all justify choosing more space. Whatever the volume, install and mature an effective filter before introducing the fish.

Build the aquarium around digging, cover and stability

Start with an aquarium large enough to remain stable as feeding and waste increase. OATA recommends choosing as large an aquarium as is reasonable because greater water volume makes temperature and water quality easier to keep stable. For a planned pair of smaller American cichlids, use at least 120 litres as the starting reference and increase the volume when the aquarium will contain other fish.

Choose each physical element for a reason

Fine gravel or sand follows the American-cichlid recommendation because members of the group may dig or sift the substrate while feeding or breeding. Expect the layout to change where fish move the substrate. Check regularly that displaced material has not accumulated around a filter intake or created an obstruction.

Live plants may be dug up or eaten by American cichlids. Plastic plants can provide cover without relying on rooted growth, although every item still needs to leave enough open water for normal swimming. Base the arrangement on usable space, not the number of ornaments placed in the aquarium.

Run a layout check before introduction

• View the swimming area: confirm that cover has not reduced the aquarium to narrow gaps that restrict normal movement.
• Inspect the substrate: make sure fine gravel or sand cannot block the filter intake if it is moved.
• Check every fitting: confirm that the filter and heater continue operating correctly after the final arrangement is complete.
• Test the whole aquarium: measure temperature and water quality after the equipment and décor have been running together.

Repeat the physical check during the first week because digging can move substrate after introduction. If material gathers around the intake, clear the obstruction while preserving filter operation. If cover shifts or reduces swimming room, rearrange it without adding more livestock. These checks keep the aquarium functional as the fish begins using the space.

Complete the physical layout before introduction so the filter, heater and substrate can be assessed together. Confirm that water moves through the filter, that temperature is even within the aquarium and that the fish will have access to both cover and clear swimming space. A decorative tank is not ready until its biological filtration and water measurements are ready as well.

Mature the biological filter before introduction

A biological filter is essential because fish release ammonia, which is toxic. The RSPCA’s aquarium filtration guidance explains that beneficial bacteria convert ammonia into nitrite and then into the safer end product nitrate. Nitrite is also toxic, so both ammonia and nitrite must read zero before the Topaz Cichlid is introduced.

Prepare the aquarium in advance rather than expecting a newly installed filter to process a full fish load immediately. Our first tropical aquarium guide explains how to set up and mature the system before livestock arrives.

Use a three-stage readiness check

1. Confirm operation: make sure the filter is running correctly and is not blocked.
2. Test the water: ammonia and nitrite must each be zero mg per litre.
3. Control the stocking increase: add fish slowly so the beneficial bacterial population can adjust as waste and feeding rise.

Adding several fish rapidly can leave too few nitrifying bacteria to deal with the increased waste. OATA calls the resulting ammonia or nitrite rise “new tank syndrome”; it can make fish ill and may be fatal. Avoid that pressure by treating every added animal as an increase in biological load, even when the aquarium looks clear.

Use the first week to check the new load

Test the aquarium after introduction instead of assuming the mature filter has adjusted immediately. Record ammonia and nitrite alongside feeding and behaviour so any change can be matched to the new biological load. If either toxic compound rises above zero, pause all further stocking, review feeding and restore water quality before considering another addition.

A clear-looking aquarium is not a substitute for those results. Filter bacteria respond to the waste entering the system, while visible clarity only shows that suspended material is limited. Continue checking the filter for blockages and confirm that it is moving water normally each day. This separates three decisions that are easy to confuse: whether the water looks clear, whether the equipment is operating and whether biological filtration is processing the waste.

Before introduction, check temperature against the 22–27°C working range and confirm the other measured values are within the stated envelope. Do not use the fish’s compact dispatch measurement as a reason to skip maturation. A 3–4 cm fish still produces waste, and the filter must already be functioning when feeding begins.

After introduction, resist the temptation to add more livestock quickly. Continue testing while the filter bacterial population adjusts to the changed load. A stable result is zero ammonia, zero nitrite and controlled nitrate, not simply a filter that is moving water.

Measure the water before deciding whether to adjust it

Use 22–27°C, pH 6.5–8.0, 4–12°dH general hardness and 3–10°dKH carbonate hardness as the routine working envelope. The FishBase environmental temperature of 23–26°C sits within that wider aquarium range. Keep the aquarium stable inside the envelope rather than moving values repeatedly in pursuit of one exact point.

Read our water chemistry guide to understand what each measurement represents, then enter measured values into the water matcher when comparing the aquarium with the stated ranges.

Work from the tap-water baseline

The nitrate limit is relative to the normal tap-water reading. If the tap water measures 10 mg/l nitrate, adding 20 mg/l gives an aquarium ceiling of 30 mg/l under the OATA recommendation. If the tap result is 25 mg/l, the corresponding ceiling is 45 mg/l. Record both readings so a rising aquarium value is not confused with nitrate already present in the source water.

A result of 25°C, pH 7.4, 8°dH and 6°dKH sits within all four working ranges. That set of results calls for stability and routine monitoring, not adjustment merely to reach the midpoint. Ammonia or nitrite above zero requires immediate attention even when temperature, pH and hardness are within range.

Compare results as a set

Suppose the temperature is 25°C and pH is 7.4, but nitrite is above zero. The in-range temperature and pH do not cancel the toxic nitrite result; water quality needs attention before another fish is introduced. Conversely, when ammonia and nitrite are zero and every routine value sits within its range, preserve that stability rather than making an adjustment simply because a result is near one end of the envelope.

Use the same test sequence each week so comparisons remain meaningful: check the tap-water nitrate baseline when needed, measure the aquarium, record the result and note any recent stocking or feeding change. A written sequence makes a gradual rise easier to recognise than isolated readings remembered without dates.

Test after any unexplained change in swimming, breathing, appetite, colour or hiding. Water quality is the first practical check because American cichlids can be stressed by even small amounts of ammonia or nitrite.

Feed one controlled meal each day

American cichlids are generally omnivorous and often prefer meaty foods. Use a specialised cichlid pellet or granule as the regular prepared food, then add suitable frozen or freeze-dried items for variety. For a smaller American cichlid, OATA identifies daphnia, brine shrimp and bloodworm as appropriate examples.

Control the portion by time, not guesswork

Feed once a day and offer only what the fish can eat within a few minutes. Begin with a modest portion, watch it being taken and stop adding food when interest slows or pieces remain. This observation-based method adjusts the portion to the fish without relying on a fixed number of pellets for every food size and dispatch grade.

Adjust the next meal from what happened today

If food remains after the feeding window, make the next meal smaller rather than extending the time or adding a second feed. If the full portion is eaten promptly, continue observing before deciding whether any more is needed. The endpoint is a completed meal within a few minutes, not a container measure that stays unchanged as the animal, food form or aquarium conditions change.

Record a sudden fall in appetite separately from an ordinary portion adjustment. Check swimming, breathing, appearance and water quality before trying to tempt the fish with extra food. Adding more when interest has fallen can leave uneaten material to break down, which increases waste precisely when the aquarium needs closer observation.

Overfeeding matters because uneaten food and excess faeces break down and release waste into the water. The result increases the work demanded of the filter and can contribute to unhealthy ammonia or nitrite levels. Feeding more than the fish can finish is therefore a water-quality decision as well as a diet decision.

Use frozen and freeze-dried items as supplements rather than turning every meal into a large mixed feed. Change one element at a time and keep the total amount within the same few-minute limit. That makes it easier to identify whether reduced intake reflects a disliked food, an excessive portion or a wider health or water-quality change.

Complete the weekly water and filter checks in order

At least once every week, carry out a partial water change of 25%. Use a siphon to remove solid waste from the substrate, especially where fine gravel or sand has collected uneaten food or faeces. Treat replacement tap water with conditioner before it enters the aquarium so chlorine or chloramine is removed.

Calculate the change from actual water volume

These examples show the arithmetic for a 25% change. Use the aquarium’s actual water volume when practical because substrate and décor occupy some of the nominal capacity. Carry out this 25% change at least once each week while matching the replacement water appropriately to the aquarium.

1. Test ammonia, nitrite and nitrate before the change so the result shows what developed during the week.
2. Siphon the planned volume while removing visible solid waste.
3. Keep some removed aquarium water if filter media needs a light rinse.
4. Condition the replacement tap water before adding it.
5. Check the filter for blockages and confirm normal operation after refilling.

Never rinse biological filter media under the tap. Chlorine or chloramine may kill the beneficial bacteria established in the media. When cleaning is necessary, rinse the media lightly in water removed during the partial change; this reduces bacterial loss while clearing loose debris.

Finish with a post-change check

After refilling, confirm that the filter has restarted normally and is not obstructed by shifted sand, gravel or debris. Compare the aquarium with its usual operating condition rather than assuming that completing the water change has completed the maintenance. A filter that remains stopped or blocked cannot perform its biological role.

Keep the test result, changed volume and any filter cleaning in one weekly note. If nitrate rises from one week to the next, that record helps you compare feeding, waste removal and the actual amount of water changed. If ammonia or nitrite appears, treat that as a separate water-quality problem rather than waiting for the next routine maintenance day.

Test at least weekly even when the fish appears normal. A working filter should keep ammonia and nitrite at zero, while water changes and controlled feeding help keep nitrate within 20 mg/l of the normal tap-water level. Record the results so a gradual shift can be recognised before it becomes a large change.

Respond to changes before they become larger problems

Learn the fish’s normal swimming, feeding, breathing, colour and use of cover after introduction. Individual behaviour can vary, so a change from that animal’s usual pattern is often more useful than comparing it with a generic description.

Use routine moments as checkpoints

At the daily feed, check appetite, swimming and breathing while the fish is visible. During the weekly water change, inspect fins, scales, body condition and colour, then compare the observations with the previous week. After adding any livestock, watch for a change in aggression or hiding as well as changes in the water tests.

If a health change persists, test temperature, ammonia, nitrite, nitrate and the other routine values, record what has changed and contact us for further guidance. Do not increase feeding to compensate for reduced appetite; uneaten food adds waste while the cause is being assessed.

Keep the response factual. Note when the change began, whether feeding altered, which water values moved and whether another fish was recently introduced. Those observations allow the aquarium conditions and the animal’s behaviour to be considered together without guessing at a treatment.

Screen every proposed companion instead of using a fixed list

American cichlids vary in temperament, and some members of the group may be very aggressive. Treat Topaz Cichlid compatibility as an individual stocking assessment rather than a promise based on a common name. A proposed companion must pass the adult-size, water, behaviour and space checks at the same time.

OATA notes that calmer American cichlids such as angelfish and severums can sometimes be mixed in a robust community with larger shoaling fish. It also says more aggressive species must be kept alone or with equally aggressive cichlids. Those examples demonstrate why the temperament assessment comes before a tank-mate recommendation; they do not classify every American cichlid in the same way.

Reject a plan when one check fails

A shared temperature range is not enough when adult sizes, social requirements or behaviour do not fit the aquarium. Likewise, generous water volume does not make incompatible water ranges overlap. Work through every row before introduction and treat the first failed condition as a reason to revise the plan rather than relying on the remaining checks to compensate.

For example, a companion that shares 22–27°C still needs suitable pH and hardness overlap, enough adult space and a stocking pattern the aquarium can support. After those paper checks pass, observed feeding, swimming, hiding and aggression decide whether the combination continues to work. Compatibility remains an ongoing decision because behaviour and biological load can change after another fish is added.

Most American cichlids do better singly or in pairs, while some species have different social requirements. One purchase here provides one Topaz Cichlid, and buying two animals does not by itself create a compatible pair. Plan the stocking arrangement from aquarium capacity and observed interaction rather than assuming that dispatch size or an unsexed selection predicts a stable relationship.

Manage stocking slowly and act on conflict signals

Before combining fish, write down the aquarium volume and dimensions, current temperature, pH and hardness, filter maturity, existing species, numbers and adult sizes. Contact us with that complete stocking plan for a compatibility assessment. A list of names without adult sizes or water measurements is not enough to judge the combined demand on the aquarium.

Add biological load gradually

Increase the fish population slowly so beneficial bacteria can expand as feeding and waste rise. Test ammonia and nitrite after a stocking change and require both to remain at zero. Do not treat normal social behaviour as proof that the filter is coping; behaviour and water quality are separate checks.

Use staged checkpoints after a change

At the first feed, check that each fish can reach food and that no individual is prevented from eating normally. During the following daily observations, compare swimming, hiding, breathing and aggression with the behaviour seen before the addition. At the next weekly maintenance session, review those observations alongside ammonia, nitrite and nitrate results.

Keep the new stocking level unchanged while making that assessment. Adding another animal before the first change has been evaluated introduces another source of waste and another set of interactions. A stable checkpoint requires zero ammonia, zero nitrite, controlled nitrate and behaviour that still allows every fish to feed and swim normally.

Avoid mixing a fish that proves aggressive with calmer companions. The American-cichlid recommendation is that aggressive species be kept alone or with equally aggressive cichlids, but any such arrangement still requires enough aquarium capacity and a mature filter.

Do not solve an uncertain mix by adding several more animals at once. That increases both the behavioural variables and the biological load, making it harder to identify why hiding, aggression, appetite or water readings changed. Slow stocking keeps each decision observable and gives the filter bacteria time to respond.

Answer the key Topaz Cichlid questions

What is Amatitlania myrnae?

It is a freshwater cichlid from Central America, recorded from Atlantic-slope waters in Costa Rica and Panama. FishBase records a maximum of 8 cm standard length, while the trade identity Cryptoheros myrnae may also appear in aquarium catalogues.

How is one Topaz Cichlid sold?

One purchase quantity provides one animal. Choose the required dispatch size using the live size selector, and do not treat that measurement as the fish’s eventual adult size.

Which Topaz Cichlid sizes can I select?

The dispatch grades are 3–4 cm, 5–6 cm and over 6 cm. Plan the aquarium and companion sizes around the recorded adult maximum of 8 cm standard length.

What aquarium setup does a Topaz Cichlid need?

Use a mature, filtered aquarium with fine gravel or sand and useful cover. OATA recommends at least 120 litres for a pair of smaller American cichlids under 15 cm; treat that as a planning reference and choose more space when the stocking assessment requires it.

Should a Topaz Cichlid be kept singly or in a pair?

OATA says most American cichlids do better singly or in pairs, although some species differ. One purchase provides one animal, and selecting two unsexed fish does not guarantee that they will form a compatible pair.

What water does it need?

OATA’s group guidance for American cichlids gives 22–27°C, pH 6.5–8.0, 4–12°dH and 3–10°dKH rather than a species-specific optimum. Keep ammonia and nitrite at zero mg/l, and keep nitrate within 20 mg/l of the normal tap-water level.

What should this fish eat?

Feed a specialised cichlid pellet or granule once a day, offering only what it eats within a few minutes. Frozen or freeze-dried daphnia, brine shrimp and bloodworm can supplement the prepared food for a smaller American cichlid.

How should it be prepared for introduction?

Mature the biological filter first, confirm ammonia and nitrite are zero mg/l, and follow OATA’s American-cichlid group guidance of 22–27°C before introduction. Increase the aquarium population slowly so beneficial bacteria can adjust as feeding and waste rise.

How do I assess compatibility for this fish?

Check every proposed companion for adult size, overlapping water ranges, temperament, social arrangement, filtration demand and aquarium capacity. American cichlids vary in aggression, so no companion should be treated as universally suitable.

Consult the identity and care references