Fish for 5 Gallons and Under | The PNW Custom Stocking Guide
Updated: Nov 3
One fish can bring a desktop reef to life. The fun part is finding a fish whose behavior fits the space you’ve built for it. We put together this guide so you can start with your aquarium and see which fish to research. You’ll find our smallest goby picks, options to consider as you move up in tank size, and a few popular fish we’d save for a larger setup.
Many gobies under 2" lack a swim bladder, the organ that helps fish control their buoyancy. These gobies can swim, but they often spend much of their time perched on rockwork, resting on the sand, or making short trips from a burrow. That’s one reason why a tiny, perching goby can be a suitable fit for a desktop reef.
Choose Your Aquarium
Start with one fish in an established desktop reef. Each row gives you options to choose from. As you move up in tank size, you can also consider the fish listed for smaller tanks if your setup meets their needs.
PNW Custom Desktop Aquarium | Fish to Consider |
A carefully chosen Eviota or Trimma Goby, Green Banded Goby, Flaming Prawn Goby, or Panda Goby. | |
For a permanent setup, start with the 40oz shortlist. | |
The 40oz shortlist, plus a Clown Goby, Neon Goby, Red Head Goby, or Tiger Goby. | |
The same shortlist as the 1 Gallon, with extra room to arrange rockwork and create hiding spots. | |
The smaller-tank shortlist, plus Yasha, Hi Fin, and Sharknose Gobies to research. Check the exact species, adult size, and supplier’s care requirements before buying. See the note on Wheeler’s Goby below. | |
Start with the 3.3 Gallon shortlist. If the tank is mostly frag racks, choose a fish whose habitat you can actually provide. Burrowing gobies need a suitable sand area and stable rockwork. | |
The smaller-tank shortlist gives you the most straightforward choices. See the notes below on Court Jester and Watchman Gobies, clownfish, and cardinalfish before choosing one for this tank. |
Before you bring a fish home
Wait for a cycled, stable tank. It is important to wait for the cycle before adding a fish to your aquarium. This process can be assisted by adding live rock and/or live sand.
Ask to see the fish eat. Find out exactly what food the seller is using and have it ready.
Match the aquascape to the fish. A perching goby needs sheltered rockwork. A shrimp goby needs a place to burrow.
Keep the stocking simple. One well-chosen fish gives you room to enjoy its behavior and makes it easier to tell if it’s eating. A coral-and-invert reef is also a great fit for any of these tanks.
The Full Fish List
Fish Name | Max Size | Where To Start | What To Know |
1-1.5" | 40oz and up | A small goby to look for if you enjoy watching a fish move between rockwork and little perches. Give it places to retreat while keeping feeding spots easy to observe. | |
1" | 40oz and up | These are two genera with many species. Confirm the exact fish, how large it gets, and what it’s eating. Choose one you can reliably see and feed. | |
Flaming Prawn Goby | 1" | 40oz and up | A tiny, secretive fish. A dedicated setup makes it easier to see whether it’s getting food. Expect it to spend time out of sight. |
Panda Goby | 1" | 40oz and up | Confirm the exact species, its shelter needs, and what it’s already eating. A fish this small can be hard to monitor in a tank full of hiding places. |
1.5" | 40oz and up | A beautiful but expensive and hard-to-find goby. It needs a suitable sandy burrow area. | |
1.5" | 1 gallon and up | Identify the species first. If you keep SPS corals, especially Acropora, check for potential nipping or irritation where the fish perches. | |
1" | 1 gallon and up | A captive-bred fish that’s already eating prepared foods. Use a secure lid and check gaps around cords and equipment. | |
1.5" | 1 gallon and up | A striking captive-bred goby with a lot of personality. | |
2" | 1 gallon and up | A small goby with a translucent body patterned with bold brown vertical bars running from head to tail. | |
Masked Goby | 1.5" | 1 gallon and up | Offer appropriately sized food and watch to make sure it’s eating after it settles in. |
Pygmy Hawkfish | 2" | 3.3 gallons and up | A tiny perchlet with a bold geometric pattern. Give it shaded rockwork with small caves. |
2" | 3.3 gallons and up, dedicated cooler-water aquarium: 60-70 degrees | Save this one for a setup designed around its unique temperature needs. | |
2" | 3.3 gallons and up, with a suitable burrow area | Consider one fish in an established tank with a secure lid, sand, and stable rockwork. If you want a pistol shrimp partner, verify the pairing and account for the shrimp when planning the setup. | |
2" | 3.3 gallons and up, with a suitable burrow area | Make sure food reaches the fish near its shelter, especially while it settles in. | |
1.5" | 3.3 gallons and up | Give it sheltered perches and a secure lid. | |
2-3" | 5 gallons and up | A grazing goby that benefits from mature rock and sand. Published care guidance starts at 10 gallons. | |
3" | 5 gallons and up | Ask for the scientific name. “Watchman” covers several fish, and a small juvenile can give you the wrong impression of how much room the adult will need. | |
3" (Percula) | 5 gallons and up | Our earlier stocking guide discusses very small juveniles in the 5 Gallon XL. | |
3" | 5 gallons and up | Plan around adult size and swimming room. |
Can a juvenile fish live in a smaller tank temporarily?
Some juveniles can spend time in a smaller aquarium when the setup meets their current needs. That may be six months to a year in some cases. Growth and behavior vary, so use the fish’s condition, activity, and feeding as your guide and move it sooner if needed.
Our 3.3 Gallon Desktop Aquarium, 4 Gallon Lagoon, and 5 Gallon Small-In-One XL can also make great quarantine tanks. Use one to observe a new arrival and make sure it’s eating before introducing it to your display, or as a separate hospital tank to monitor and treat a sick fish before returning it. Keep the setup simple, with an easy-to-clean hiding spot and equipment dedicated to quarantine. If treatment is needed, dose medication based on the actual water volume and follow the treatment directions before moving the fish.
Want to see a few of our favorite tiny gobies up close?
If you’re planning the whole reef, including corals, snails, and shrimp, start with What Can Live in a Desktop Reef Tank?.
