Matt_

I am not a Corydoras expert (I only keep 4 varieties right now), but those do look like sterbais only with a more pronounced central line and no orange stomach like this (they would be stressed if it is just the two of them because Corys want to be in a large shoal): My next guess would be San Juan (Corydoras bilineatus) Corydoras, but the ones that I have seen do not have those markings on the tail fin. Elegans is another possibility with the same tail marking issue. They do not have the black dorsal fin of triliniatus, napeonsis, or leopardus so I do not believe it is one of those.

I lost the larger of my two Odessa Barb males last night in my community 65 gal. aquarium, and I would like to get an opinion of why this happened and if I should make changes to the current group of Odessa Barbs. Nothing is obviously wrong with the deceased fish other than some apparent blood at the gill area (very difficult for me to tell), photos attached at the bottom of this post. The fish was eating well, behaving normally, and healthy the last time I saw him. None of the other tankmates are behaving differently or showing symptoms of disease. My current theory that the male died from running into something in the tank, but there is also not much there to hit (one clay pot, a large piece of driftwood, some pleco/loach caves, heater, substrate, and tank lid). The male was part of a breeding community of 2 adult males and 4 adult females that I purchased from my LFS that came from someone giving up a mixed barb tank; the group breed in the QT tank and now I have 30-40 growouts. The Odessa Barbs all established their own territories in the tank and the male that I lost was the larger and more aggressive male toward the females when breeding. They did not really show any aggression towards their tank mates after they initially established their territories in the 65-gal tank. I have noticed that some of the females have lost scales from the males chasing the females during breeding but have remained in good health. Tank: 65-gal 2'Hx1.5'Wx3'L - running for 2.5 yrs Purchase Date for Odessa Barbs (as adults): 2 mo. Approx. Time in 65 Gal. Tank: 6.5 wk. Water Parameters (measured this morning after feeding - stable/biweekly water change - regular water change scheduled for this weekend): Temp. 79F pH: 6.8 Ammonia: 0 ppm Nitrite: 0 ppm Nitrate: 40-50 GH: 9 deg. KH: 2 deg. Food - Tank gets a mix of: Northfin Community Flake Northfin Community Formula (0.5mm pellets) Northfin Bug Pro (2mm pellets) Xtreme Scrapers (14mm wafers) Tank Mates: Guppies Molly - Single Adult Male Paleatus Corys Clown Loaches Bristlenose Plecos L-066 Pleco Otocinclus Photo of Deceased Barb taken this morning (Warning - Deceased Fish😞

It was the K500 Mixing Valve from Hass Manufacturing Co. (specialty product, extremely expensive): See 5:10 Urban Fish Farm Temperature Controller Video: The manifolds were the standard Orbit Heavy Duty Sprinkler Valves from the hardware store (Amazon.com : Orbit 57250 2-Valve Heavy Duty Preassembled Manifold : Automatic Lawn Sprinkler Heads : Patio, Lawn & Garden). 0:20 of the Video:

For two ten-gallon tanks I would use oversized heaters (like 100W), a tight-fitting lid, and insulate the bottom (if they tanks are not located on the counter) and sides of the tanks. The insulation is the most effective if you can get all the air gaps sealed up with a product like trim tape (based on your use I recommend going for efficiency over looks).

Never seen red blotch disease before but the photos on Google (may not be accurate) sure seem resemble the photo of the fish above.

Dead space for water flow is not an issue; oxygenation is different. Please don't drill holes in your decorations. I have a 38-gallon heavily planted aquarium with 100 or more guppies and about 30 Paleatus Corys that only has two airstones for aeration and tons of dead spaces everywhere. I also have a 65-gallon tank with a huge hollow log with plecos, corys, and clown loaches living nook and before that the same fish lived in a castle decoration.

Ok, responses are what I expected; looks like temp. water, food, etc. is normal and within range for those Corys. As a side note, I have gotten to the point where I just shake all the liquids when I use the API test kits so that I don't have to remember which ones require shaking 🙂. Low oxygenation may have been the issue even with a powerhead. Two powerheads is a lot of flow for a tank that size. A quick way to check is to see if the tetras and plecos are all at or near the water surface at night when they are typically less active (checking with a flashlight in a dark room). If there is an oxygen deficiency then the fish will be behaving differently (i.e.: swimming lethargically, breathing surface air). After that I am out of ideas and hope that transitioning the fish to the 55 gal fixed the issue.

That is a hard question that really depends on the child's interests. The first thing that comes to my mind is shrimp or snails for aquarium options or carnivorous plants or an ecosystem (similar to an ecosystem in a jar) for nonaquarium options using a tightfitting lid on the tank. I have two boys about this age, but they only want an axolotl 🙂. The nano fish that would fit in a 2.5 gal tank and have enough swimming room will probably not be interesting to the child and keeping a 2.5 gal aquarium is very unforgiving for whoever does the maintenance.

You should be able to stray current if you have a multimeter, but I doubt it is the issue since the fish are not behaving erratically. Just trying to think through why only the Corys are not doing well in only the 36 gal tank vs. the 55 gal. @nabokovfan87 oxygenation comment also is worth considering. One way to check is to see if the tetras and plecos are all at or near the water surface at night (with no stray light).

Agree with tightfitting lid and back/side insulation to cut down on heat loss using a heater in the tank. I also recommend insulating the bottom of the tank too (I used XPS with thin plywood on top for a standard Aqueon tank with a plastic bottom frame). You loose quite a bit of heat through the bottom of an uninsulated tank (cold bridge). You did not say what size these tanks or the room are, so it is hard to say whether heating the tank or the room makes more sense, but this is what I did when I had my tank in a basement with a similar winter temperature. I also recommend you confirm the basement temperature in advance if these tanks are over 75 gals. because it gets expensive to run high wattage heaters continuously.

Sorry for your loss. Those are nice looking tanks. I have a question and a couple of things to check from personal experience. I have kept Corys with sharp rocks and substrate in a 2' deep tank for years so I tend to doubt either is contributing to the issue. Were the API test results in the initial question identical for both aquariums? It is strange that there is no measurable ammonia in the 36 gal. at this point with those losses - I usually get minor indication from the API liquid Ammonia test kits no matter what I do. Recommend ensuring that the testing liquid is well shaken prior to testing if you are using the API liquid test kit and retest the 38 gal for Ammonia and Nitrite. If the Corys are doing well in the 55 gal. using the same well water, then the issue should not be an undetectable parameter with the well water (like salt, heavy metals, or industrial pollutants). Other quick checks: recommend independently checking the tank temp. again to rule out a faulty heater/thermometer if you are using an electronic thermometer. Confirm all foods, especially the sinking pellets/wafers, are unspoiled and less than a year old (preferably younger than that, but it is a start). The water temperature of the well water could be a factor at a 40% water change if it is significantly warmer or colder than the tank water assuming you checked this by feal at the water changes. If the water tests for Ammonia and Nitrite are still reading at 0 in the 38 gal. and GH/KH is not elevated one idea would be to check for stray current from the powerhead/heater.

Also check your water before you put any chemicals in it. If you start with ammonia from your the tap the ammonia may actually be higher in the aquarium from water changes. I think of this every time since my tap water has 0.25 ppm to 1 ppm ammonia in it before I do anything to it and the planted aquarium cleans up the water after I add it 🙂

I recommend trying this with a couple of basic Lego bricks first to understand the time involved before going all in on an underwater build. You are going to have to use a pipette or a syringe to remove the air from every hole in every brick since it is really hard to get all of the air out of each brick. It still might be really cool to see something like the LEGO City Ocean Exploration Ship - 60266 floating in a tank though. This actually gives me an idea for the old 38 gal tank that is sitting in the basement.

The standard 2x4 stand design is fully scalable to support the 75 gal tank on the top and smaller tanks on the bottom. You just need to decide how you want all of the tanks oriented. There are more minimal designs but this basic design is my favorite since you can build this with the basic tools and skills. The design can also be wrapped and have trim added if desired. I recommend looking up: "HOW TO: Build an Aquarium Stand/Canopy" on YouTube to see some of the build guides. There are also some good threads on this Forum.

The best part about the Northern Puffer is that it is a local fish (to VA). My kids caught a live juvenile in a bucket on the last trip to the beach. (Before anyone gets concerned I made sure that the fish was never out of the water and promptly released as soon as everyone was done admiring it.)