quikv6

I'm not sure, to be honest.

I would try Sulfaplex over Neoplex if you can get it. I have treated Columnaris before with Sulfa-based meds, and thankfully have been successful. Sometimes they work when Kanaplex+Furan 2 combo doesn't, though Kanaplex is generally considered a stronger medication.

That looks like body slime. I like the Kanaplex suggestion, but you can also try API Fin and Body Cure.

As for heaters, you will find a variety of opinions, though the one consistency you will find is that they are inconsistent. Personally, I use 2 heaters (200w each) in a 75 gallon, and I have one set a few degrees lower, and it almost never turns on. It seems the one 200W heater is fully sufficient heating 75 gallons to 78.3 degrees, when the room temp is about 68-70. Also, the heater actually cycles (on/off) less, which I prefer. If you get a single heater for the 29 gallon, and the watts are high, it will cycle quite a bit. The theory is that the constant cycling is what kills the heaters. You would probably be okay with a single 100-150W, and you can get an Inkbird controller as a failsafe.

I agree with the above. I have livebearers, and I believe a PH of 7.6 should be fine, but your KH is quite low, which can result in PH fluctuations. Crushed coral does work, but if you are doing large water changes, it takes time for the parameters to "catch up" , so to speak. Here's what I do, since I have VERY soft water with low KH out of the tap. 1) Crushed coral in the substrate 2) Crushed coral in a HOB filter. (It dissolves faster due to the flow through it.) 3) Wondershell (for GH)...though your GH looks great. 4) Baking soda (BE CAREFUL if you go this route!) added to the water during a water change. This raises the KH/PH of the tap going in to match what is in there already. If you decide you want to try this, test (I repeat...test) a given amount of baking soda in a 5 gallon bucket first, to see exactly what effect it has on the PH/KH. A given amount will have a different effect on different water. I have found that 1/2 teaspoon per 5 gallons gets me from 6.8 to 7.6, and brings the KH from 40 or below to around 100. But that is on my water. Definitely test first.

(apologies....wrong post)

You can also try a sulfa med, such as API Triple Sulfa or SulfaPlex. These are usually pretty mild meds. I have had luck with Triple Sulfa working against Columnaris when Furan2/Kanaplex combo didn't. If I posted this earlier in the thread, my apologies. Just throwing it out there as a possibility.

Welcome to the hobby! It is very enjoyable. It can also be a bit stressful (especially at the beginning), but don't let that discourage you. The more you learn, the more confidence you gain, and the easier and more rewarding it gets. It is great that you tested GH, KH, and PH. Being it sounds like it is a brand new, uncycled tank with multiple fish, I think ammonia and nitrite would be #1 and 2 on things to test. They can both be toxic and deadly to fish. Feed very lightly, if at all, if you don't yet have an ammonia test. You can also buy a bottle of seachem prime, or fritz complete. These 2 declorinators also do more than just dechlorinate. (Speaking of which...chlorine/chloramine is toxic as well...make sure to dechlorinate) Prime and Complete also detox ammonia for 24-48 hours, thus "neutralizing" it's harmful effects. If you don't have an ammonia test, you can just add a double dose of the above to help detox any ammonia. Most importantly, good luck, and enjoy the process!

If there is drive to eat, and then spitting out, stubborn parasites are a real possibility. I have 2 cases of this recently, with the same spitting symptom, and sunken bellies. I tried General Cure with no luck. I even tried Levamisole, with no luck. The only this that worked in these two cases was Flubendazole. In both cases, after 2 doses (3 days apart), the fish were able to keep food down, with no spitting. Weight gain immediately followed. On the negative side, Flubendazole is not the easiest to work with, and is tricky to find as well.

Have you tried frozen bloodworms?

I agree...don't give up at all. You got this! One quick observation: You didn't post your GH or KH. Do you know what they are? It may be irrelevant, or it may point to a disparity between your water and the water the fish were coming from. Also, it is peace of mind to know that your KH is higher than zero, as no KH could result in a PH crash/rapid swing, etc.

What I have experienced with wasting disease is that they will always be interested in food. If they eat it, they don't gain weight due to the parasite. If they spit it out, it's because they physically can't swallow due to inflammation as a result of the parasite.

That one looks like it may have wasting disease/sunken belly. Have you observed if it is eating, and keeping food down? That may yield some clues. Generally, Levamisole is the go-to med for wasting disease. I have used it successfully, though I have had 2 stubborn cases recently, where the Levamisole didn't seem to work. I used Flubendazole, and it worked. In both of those cases, the fish just spit out the food, and couldn't swallow it. I will say, Levamisole is a bit easier to work with.

Sounds like a parasite or possible wasting disease. The white mold sounds like fungus. Given you may have narrowed it down a bit, I would go further than just the preventative dose that marinates for a week. I think Paracleanse (or General Cure) could (keyword:could) address the skinniness/parasites. Follow the instructions on the box, which go further than a preventative dose. And for fungus, Ich-X may have a minor effect. With that being said, I much prefer API fungus cure, if it is indeed a fungus. You can try Ich-X first if you have it. If the skinniness doesn't get better (monitor if they are eating, or trying to eat and spitting out), then you may need a different anti-worm med, such as Levamisole or Flubendazole.

I also don't believe you will have any issues with an "overdose". I have dosed, and then added more to food twice in that same day. No issues. The only other thing I can add is that recently I have had 2 really stubborn cases of wasting/sunken belly. I am not sure if that is what you are treating, but in both cases Levamisole did not yield any positive results. I switched to Flubendazole both times, and both times yielded positive results after the first day. That may or may not be applicable here, but just wanted to mention it.

Maracyn 2 is quite different than Maracyn....which one did you use? I don't know if Maracyn 2 can work alongside the other 2 meds. And as others have mentioned...that Nitrite level is too high. Ideally, it should be zero. Getting it down with a partial water change or two would be a great first step for a hope of recovery.

Ammonia and Nitrite should be zero, ideally. Nitrates should be measurable. Any level of ammonia or nitrite can cause varying degrees of stress, illness, or worse. If you can post specific parameters, including GH, KH, and PH, that may significantly help point towards a potential culprit causing the issue. Also, please let us know how long the tank has been set up and operational.

What is the PH out of the tap? I noticed 0 KH, which can cause PH swings or a PH crash. That could cause enough stress to take them out. Additionally, if they are new to you, and came from water with vastly different parameters, such as a much higher PH (which guppies would probably appreciate), they could be experiencing some shock, which can take a few days to show.

if you have any level of nitrites, that could be why. You would want both ammonia and nitrites to be zero, since they are both harmful to fish. If you are showing nitrites, the tank is still cycling....in which case partial water changes (dechorinated) and a bottle of Prime (a declorinator that can also detox ammonia and nitrites for 24-48 hours) will be your friend until your tank completes cycling.

I think that the fry I have lost in ACO sponge filters didn't get sucked-in, per se, but either wandered in the coarse sponge while looking for grub, or were chased in there by an adult, and went to hide in the sponge. Once they were embedded a few pores deep, they just couldn't get through the maze to get out, unfortunately.

I have lost quite a few fry in the ACO sponge filter. It isn't common, but has happened. In a few cases, I was lucky enough to notice it time, and carefully cut around the coarse sponge to free the fry.

A few concerning things related to your parameters: 1) 0 buffer could lead to PH swings, or a PH crash. What is your PH out of the tap? 2) 200 nitrates seem quite high....very high actually. Most folks try to keep it below 40ppm, as a general rule. How long has the tank been established, and what is your water change schedule and stocking? Sorry about the questions, but they could help point towards the potential issue at large.

The fry should be okay. If the general cure doesn't work (which, if it is indeed wasting disease, may not), then you may have to go with Levamisole.

You can also cut the uplift tubes, or remove them altogether, if you want more bubbles in the directly in the water.

Given the 4 foot length, I think you'd be much better doing the 2 mediums, as it would help eliminate any dead spots, and increase surface agitation. That worked for me on a 40 long tank (also 4 foot). Also, I have a 75 gallon (again, 4 foot tank), where I have 2 mediums in the rear corners, and a small that is dead center, both length and width-wise. If you don't mind having a sponge filter in the middle of everything, that may be a good idea, given the longer width to your tank.