Red Fin Hillstream Loach (Pseudogastromyzon myersi)

<h2>Common Name</h2>
<p>Myer’s Hillstream Loach / Red Fin Hillstream Loach is a small, rock hugging grazer from fast water streams, built to live where most fish would get swept downstream. In the aquarium trade it may also be sold under names like Chinese hillstream loach, Chinese butterfly pleco, or Hong Kong Otocinclus, depending on the seller.</p>

<h2>Origin and Habitat</h2>
<p>This species was originally described from Hong Kong and is associated with clear, fast flowing hillstreams in southern China. It is commonly reported from unpolluted upland stream habitats in Hong Kong, and it is also reported from parts of Guangdong Province in southern China.</p>
<p>In the wild, it lives in shallow riffles and runs with rocky bottoms, boulders, and gravel, with very high dissolved oxygen and constant surfaces to graze. Expect strong current, cool to mild subtropical temperatures, and a food web centered on algae and biofilm rather than leaf litter and mud.</p>

<h2>Biotope</h2>
<p>For a true same water, same neighborhood setup, think Hong Kong upland tributaries, steep ravines with riffles and cascades, and occasional deeper pools. Build the aquarium around rock, current, and oxygen, then let biofilm develop on purpose.</p>

<p>Examples of native hillstream fish recorded from Hong Kong upland stream communities include:</p>
<ul>
  <li>Broken band hillstream loach (<em>Liniparhomaloptera disparis</em>)</li>
  <li>Striped loach (<em>Schistura fasciolata</em>)</li>
  <li><em>Rhinogobius</em> gobies, such as <em>Rhinogobius duospilus</em></li>
  <li>Flat headed loach (<em>Oreonectes platycephalus</em>)</li>
  <li>Stream barbel minnows, such as <em>Acrossocheilus</em> species</li>
</ul>

<p>For close to the same nearby basin context in southern China, reports also place this species in parts of Guangdong, including systems such as the Dongjiang and Rongjiang. Neighboring fast water communities in that region follow a similar theme, small stream cyprinids, gobies, and loaches adapted to current.</p>

<p>Plants in true riffles are often limited because flow and scouring favor algae and periphyton over rooted growth. In an aquarium, use tough attached plants as stand ins, such as Anubias, Bucephalandra, Microsorum, or mosses, and keep most of the footprint as stone grazing lanes.</p>

<h2>Temperature and Water Conditions</h2>
<p>Aim for cool to mild subtropical water with excellent oxygenation. A practical temperature range is about 64 to 75°F, which is about 18 to 24°C.</p>
<p>A practical pH range is about 6.0 to 7.5. Water hardness can be soft to moderate, and many keepers do well around 4 to 12 dGH. Clean water, strong circulation, and high dissolved oxygen matter as much as any number on a test kit.</p>

<h2>Appearance and Size</h2>
<p>This is a classic hillstream body plan, flattened, wide pectoral and pelvic fins, and a sucker like underside adapted for gripping rock. Maximum length is commonly listed around 2.4 inches, which is about 6 cm, with many aquarium fish staying slightly smaller.</p>
<p>The Red Fin part of the common name usually shows as warm edging on the fins, often most noticeable on the dorsal fin when the fish is comfortable and well fed.</p>

<h2>Diet in the Wild</h2>
<p>In nature it feeds primarily on periphytic algae, biofilm, and fine detritus scraped from rock surfaces. In other words, it is a dedicated grazer and surface picker, not a hunter of big prey items.</p>

<h2>Feeding in Captivity</h2>
<p>In a mature river style tank, you want to see it grazing all day. Supplement that grazing with a simple rotation:</p>
<ul>
  <li>Sinking algae wafers and small sinking pellets that hold together in flow</li>
  <li>Gel foods pressed thinly onto smooth stones</li>
  <li>Blanched zucchini, cucumber, or spinach in small amounts</li>
  <li>Frozen cyclops, daphnia, or baby brine shrimp as a supplement</li>
  <li>Occasional frozen bloodworms as a treat, not the main course</li>
  <li>Powdered foods for grazers, used sparingly so they do not foul the tank</li>
</ul>

<p>They thrive when the tank also grows real aufwuchs, meaning the algae and biofilm layer on stones and hardscape that comes with time. A sterile, perfectly scrubbed tank looks clean, but it can be a slow starvation setup for a grazer.</p>

<h2>Behavior and Tank Setup</h2>
<p>These are peaceful fish, but they are not passive. They often claim favorite grazing lanes and favorite rocks, and you may see short posturing matches that look intense but usually end with nobody harmed and everybody going back to grazing.</p>
<p>Tank setup should prioritize flow, oxygen, and surfaces. A good starting point is about 20 gallons, which is about 75 liters, for a small group, with more footprint always better than more height.</p>

<ul>
  <li>Use smooth river stones, cobble, and a few larger boulders to create grazing surface area</li>
  <li>Create both fast lanes and calmer resting pockets behind rockwork</li>
  <li>Choose cool tolerant stream species as tankmates</li>
  <li>Avoid warm water community fish, aggressive fin nippers, and large bottom feeders</li>
</ul>

<h2>Breeding</h2>
<p>This species is not widely documented as an easy, repeatable breeding project in typical home aquariums, but it is also not a hopeless mystery. It likely rewards long term stability more than special tricks.</p>
<p>If you want to try, focus on a mature river tank, excellent oxygenation, heavy grazing surfaces, and seasonal cues such as a cooler period followed by slightly warmer water changes and increased flow. Provide lots of tight crevices, undersides of stones, and sheltered cracks where eggs could be placed and protected.</p>

<h2>Breeder’s Tips</h2>
<ul>
  <li>Start with a well fed group, not a pair, and let them settle for a few months</li>
  <li>Give them more smooth stone surface area than you think they need</li>
  <li>Run strong flow, but create calm pockets so they can rest</li>
  <li>Feed frequent small meals plus grazing surfaces</li>
  <li>Use a cooler period, then increase water change volume and slightly raise temperature</li>
  <li>If fry appear, start with infusoria and powdered foods, then move to baby brine shrimp</li>
  <li>Do small frequent water changes to protect fry</li>
</ul>

<h2>Quick Facts</h2>
<ul>
  <li>Adult size: up to about 2.4 inches (6 cm) total length</li>
  <li>Recommended temperature: 64 to 75°F (18 to 24°C)</li>
  <li>pH range: about 6.0 to 7.5</li>
  <li>Water hardness: soft to moderate, about 4 to 12 dGH</li>
  <li>Minimum tank size: about 20 gallons (75 liters) for a small group</li>
  <li>Bottom oriented grazer that spends most of its day on rock and glass</li>
  <li>Habitat style: fast flowing, rocky hillstreams with very high oxygen</li>
  <li>Best results come from mature tanks with visible biofilm</li>
  <li>Diet centers on algae, biofilm, and fine detritus</li>
  <li>Temperament: peaceful, mildly territorial over favorite rocks</li>
  <li>Social structure: small groups work best</li>
  <li>Difficulty: moderate, due to high demands for oxygen and flow</li>
</ul>

<h2>Tropical Fish Co. Notes</h2>
<p>This fish is the easiest way to tell if your tank has real flow or polite circulation. If it parks on a rock and looks bored, you probably need more current. If it is surfing, grazing, and acting like it owns the place, you nailed it.</p>
<p>Build the aquarium for the river, not just for the fish. Smooth stones, high oxygen, strong flow, and time to mature, then let a little algae happen on purpose. It feels wrong the first time you do it, and it is exactly what these fish are built to eat.</p>
<p>Pro tip for new arrivals, start them on easy wins like prepared foods pressed onto rock plus algae wafers while your biofilm grows in. You want them gaining weight early, not auditioning for a fasting contest.</p>