This is very strong, but still OK
I am going to use Detect Balance to baseline the race. It is not perfect, but helps with tallying the impact for traits that are standard or not strongly synergistic. It scores races on a point scale, with a recommended range of 24 to 27 points, ideally 25.
Your Ability Score Increase, Age, Alignment, Size and Walking Speed are all standard and contribute 12 points for the ability score increases. Swim Speed 30 feet adds 2 points. Darkvision adds 3 points. You are missing a statement about Languages, unless this race does not speak any -- I'll assume common and one other maybe Aquan or Alquir, but you should spell it out. You are also missing the Creature Type (which is often overlooked but is important). I'll assume the default humanoid. That is 17 points from standards stuff.
Skinbreather combines as Amphibious, worth 2 points.The Disadvantage is not a standard thing, and such saves might happen in a desert campaign, but typically even early on players have access to creating water and it still is very situational. I'm not sure if this would deduct anything, if so, at best -1 point.
Regenerative does consume your action as you have to take the dodge action, so its not free. You should always consider how the race works when taken together with class features to optimize outcomes. Monks can take Dodge as a bonus action, but it costs a point of Ki, so there is no super easy way to exploit this. It really only matters in fights that go to the limit, and not that many do. In all other cases, you just could take that HD after the fight during a rest.
- For comparison, the Goliath's Stone's Endurance allows you to use a Reaction to gain d12+Con bonus hits once per short rest, priced at 7 points. I think due to the action economy, the Goliath feature is stronger even if it is limited to one use per fight, as you can use it in the same round you attack in, and it gives you hit points on top of your hit die.
- As another comparison point, this would be better than several free level one spells to cure wounds (each worth 3 points) which likewise consume your action but do not benefit from the Dodge bonus to AC while doing so, but those can heal on top of your hit dice, and in most fights will therefore give more value over a day. Also, you could use cure wounds to bring back one of your allies, so it is more flexible (thanks to @MJD for this last point).
- Lastly, the Dwarven Fortitude feat is a half-feat that has the same effect plus for the other half adds +1 to Constitution. Half a feat, or an ASI +1 would be worth 4 points. (Kudos for @Yakk for this).
I think this is elegeantly done, and would estimate it at 4 points of value.
Aquan Affinity: A cantrip is worth 2 points, and this is an interesting and flexible one worth full value. Speaking with small beasts is worth another 2 -- you have it limited to amphibians which is more restrictive, but you should be able to find a frog or salamander in many environments if you want (forests, coastal, rivers, swamps; only deserts, arctic and mountains would be more difficult, and there are fire and ice versions of frogs, too), so I'll treat this as 1 point instead. 3 points total.
Summing up we get 17 + 2 - 1 + 4 + 3 = 25. I may have been a bit generous on the Aquan Affinity and Skinbreather deductions, which if both were removed would push you just to the top end of the recommended range. If you wanted to be safe, you could remove something worth 2 points or so -- but all the abilities are very thematic, and feel like a pity to cut. I think this is OK, but I would strongly recommend play-testing it.