Guaymas goby
Quietula guaymasiae
The Guaymas goby exhibits a slender body with a light brown hue, featuring distinct dark spots along its flanks and a long, filamentous first dorsal fin.
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About the Guaymas goby
This is a small, bottom-hanging goby from Mexico's Gulf of California, usually found in shallow estuaries and lagoons. The really cool bit is it can do facultative air-breathing, so its built for those warm, low-oxygen, mucky spots. Its not a typical community freshwater fish - think brackish/marine lagoon goby that wants sand or mud and calm water.
Also known as
Quick Facts
Size
5.1 cm
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
30 gallons
Lifespan
3-4 years
Origin
Eastern Central Pacific (Gulf of California, Mexico)
Diet
Carnivore/micro-predator - small crustaceans and worms (amphipods, polychaetes); in aquaria: frozen/live meaty foods
Water Parameters
23-27°C
7.5-8.5
10-25 dGH
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This species needs 23-27°C in a 30 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Give them a sand-heavy tank with lots of little rock piles and tight crevices - they want to sit, wedge in, and dart, not cruise open water. PVC elbows half-buried in sand make instant hideouts and cut down on stress.
- Keep salinity steady at 1.024-1.026 and do not let pH swing (aim 8.0-8.3); they get touchy when the tank is unstable. Keep nitrate low (under ~20 ppm, lower is better) because they are bottom hangers and live in the gunk zone.
- They are micro-predators, so feed small meaty stuff: live or frozen mysis, enriched brine, chopped shrimp, blackworms (if you trust your source), and tiny pellets once they recognize them. Target feed with a pipette near their hide so faster fish do not steal everything.
- Skip boisterous tankmates like big wrasses, dottybacks, and anything that will bully a small bottom fish; they will just stay hidden and slowly waste away. They do fine with calmer fish and inverts, but assume tiny shrimp and pods are on the menu.
- They can be territorial with other small gobies and especially their own kind in tight setups, so either keep one or give a larger footprint with multiple sight breaks. If you try a pair, add them together and watch for one getting pinned to a corner.
- They jump when spooked, especially at night, so run a tight lid with no gaps around cords. Most losses I have seen are 'found crispy on the floor' not disease.
- Breeding is possible if you give a cave and keep them well-fed: the male usually guards eggs stuck to the roof/walls of a hide. The hard part is raising larvae - plan on live foods (rotifers/pods) and a separate rearing setup if you actually want survivors.
Compatibility
Good Tankmates
- Other small, mellow gobies (think neon gobies or tiny shrimp gobies). Guaymas gobies are pretty chill and mostly mind their own business on the bottom, so peaceful goby neighbors are usually fine if the tank has enough little hidey holes.
- Peaceful blennies like tailspot blennies. Similar vibe - they perch, pick at stuff, and generally do not go looking for trouble. Just make sure everyone has their own favorite rock and you are good.
- Small, non-bully wrasses like a possum wrasse. They cruise the rockwork and ignore bottom sitters, and they are usually not the type to pin a goby in a corner.
- Clownfish that are not going full 'mean host mode' (ocellaris/percula types, especially in bigger tanks). If the clowns claim one corner and the goby hangs out on the sand, they can coexist just fine.
- Small, peaceful reef fish in general - chromis, dartfish, firefish. They stick to the water column, and the goby stays low, so there is not much to argue about.
- Peaceful inverts like cleaner shrimp and most snails. These gobies are not typically shrimp hunters, and they are way more interested in little foods you feed than going after a big cleaner shrimp.
Avoid
- Aggressive dottybacks (like a purple dottyback) and other punchy rock bullies. They love to claim caves and will hassle a small, peaceful goby nonstop.
- Big territorial damsels and mean clown setups (maroon clowns, or any clown pair guarding eggs). They can turn the whole bottom half of the tank into a no-go zone for a timid goby.
- Hawkfish. They are not always evil, but they are opportunistic and tend to pick on or straight-up eat small bottom fish when they feel like it.
- Predatory 'looks safe until it is not' fish - lionfish, groupers, larger scorpionfish. If it can fit the goby in its mouth, it will eventually try, usually at feeding time or after lights out.
Where they come from
Guaymas gobies (Quietula guaymasiae) come from the Gulf of California area around Guaymas. They are the kind of goby that makes a living in silty, mucky shallows and backwater spots where the water is not always crystal clear and the bottom is soft.
That background matters because they are built for life on and in the substrate. If you set them up like a bright, bare-bottom reef showcase, they usually act stressed and you will barely see them.
Setting up their tank
Think "quiet, dim, sandy, and stable". This is an advanced fish mostly because it does poorly in brand-new systems and it hates sudden swings. Give it a mature marine tank and you will have a much easier time.
- Tank maturity: I would not put one in a tank younger than 4-6 months. Older is better.
- Substrate: fine sand (not sharp). A deeper bed lets them settle in and feel secure.
- Hardscape: a few small rock piles, shells, and rubble so it can pick a "home" and duck into cover fast.
- Flow: moderate, but avoid blasting the sandbed. They like calmer zones near the bottom.
- Lighting: they do fine under normal marine lights, but provide shaded areas. They are not a "spotlight" fish.
- Filtration: strong biological filtration and good oxygenation. They are small, but messy feeding (meaty foods) adds up.
Cover the tank. Gobies can and will jump, especially the first week. A tight lid or mesh top saves you from the classic "found on the floor" heartbreak.
I have had the best luck giving them multiple bolt-holes right on the sandline. A little cave with a sand apron in front of it is perfect. If they can sit with their belly on sand and a roof over their head, they relax fast.
What to feed them
These are small predators. Mine ignored flakes and acted like pellets were suspicious at first. Once they are settled, some will take small sinking pellets, but you will get results quicker with frozen and live foods.
- Great staples: frozen mysis (small), enriched brine shrimp, chopped krill (tiny bits), finely chopped shrimp/clam
- If they are picky: live baby brine, live blackworms (if you can source safely), or live pods to get them started
- Feeding style: target feed near the bottom with a pipette or turkey baster so faster fish do not steal everything
- Schedule: small portions 1-2x daily beats dumping a big meal once in a while
Turn pumps down for 5-10 minutes during feeding. They are deliberate eaters and the food blowing away can make them give up.
Watch the belly line. A Guaymas goby that is eating will look a little fuller behind the head after meals. If it stays pinched for days, it is either not getting food or it is being outcompeted.
How they behave and who they get along with
They are shy, bottom-hugging, and a bit "freeze and vanish". Most of the time you will see them perched on sand, then they dart back under a rock when something startles them.
Temperament-wise, they are usually peaceful, but they are not pushovers if another bottom fish tries to take their spot. In a small tank, two can squabble if there are not enough hiding places.
- Good tankmates: calm community marine fish that do not harass the sandbed (small assessors, small cardinals, calm blennies that stick to rockwork)
- Be careful with: hyperactive feeders (some wrasses, dottybacks) that will out-eat them or bully them into hiding
- Avoid: aggressive bottom dwellers, large hawkfish, big crabs, or anything that views small gobies as snacks
If you want to actually see this fish, build the tank around it a little. A "too busy" tank with fast, bold fish usually turns it into a permanent ghost.
Breeding tips
Breeding them in home aquaria is possible in the general goby sense (cave spawners, guarded eggs), but with this species you will likely run into two hurdles: getting a compatible pair and raising the larvae.
- Pairing: start with a small group in a larger tank and let them sort it out, or buy an established pair if you ever see one
- Spawning setup: tight caves or shell-like hides with a single entrance, placed on sand
- Conditioning: heavy feeding of small meaty foods, stable salinity and temperature, and minimal disturbance
- Larvae: expect planktonic babies that need tiny live foods (rotifers, then copepods) and clean, stable rearing water
If you see a fish guarding a cave and fanning, do not keep shining lights in or poking around. One bad spook and they may abandon the clutch.
Common problems to watch for
Most issues with Guaymas gobies boil down to stress, starvation, or being tossed into an immature tank. They can look "fine" while slowly losing weight, so you have to pay attention early.
- Not eating: very common after shipping. Offer small live foods to kickstart feeding, then transition to frozen
- Getting outcompeted: they lose food battles easily. Target feed at the sand and consider calmer tankmates
- Sandbed problems: dirty, compacted, or sharp substrate can lead to abrasions and infections
- Jumping: usually happens during the first week or after a scare
- Parasites from wild collection: quarantine is worth your time (and theirs)
Rapid breathing, hanging in the open, and refusing food for more than a few days is a red flag. Check ammonia, salinity swing, temperature, and oxygenation right away, then consider parasites if the basics look solid.
If you do one thing that stacks the odds in your favor: quarantine and get it eating aggressively before it ever sees the display. Once they learn your feeding routine and feel safe, they are tough in a very "quiet fish" kind of way.
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